Understanding Software Defined Storage (SDS)

Software defined storage is an evolution of storage technology in cloud era. It is a deployment of storage technology without any dependencies on storage hardware. Software defined storage (SDS) eliminates all traditional aspect of storage such as managing storage policy, security, provisioning, upgrading and scaling of storage without the headache of hardware layer. Software defined storage (SDS) is completely software based product instead of hardware based product. A software defined storage must have the following characteristics.

Characteristics of SDS

  • Management of complete stack of storage using software
  • Automation-policy driven storage provisioning with SLA
  • Ability to run private, public or hybrid cloud platform
  • Creation of uses metric and billing in control panel
  • Logical storage services and capabilities eliminating dependence on the underlying physical storage systems
  • Creation of logical storage pool
  • Creation of logical tiering of storage volumes
  • Aggregate various physical storage into one or multiple logical pool
  • Storage virtualization
  • Thin provisioning of volume from logical pool of storage
  • Scale out storage architecture such as Microsoft Scale out File Servers
  • Virtual volumes (vVols), a proposal from VMware for a more transparent mapping between large volumes and the VM disk images within them
  • Parallel NFS (pNFS), a specific implementation which evolved within the NFS
  • OpenStack APIs for storage interaction which have been applied to open-source projects as well as to vendor products.
  • Independent of underlying storage hardware

A software defined storage must not have the following limitations.

  • Glorified hardware which juggle between network and disk e.g. Dell Compellent
  • Dependent systems between hardware and software e.g. Dell Compellent
  • High latency and low IOPS for production VMs
  • Active-passive management controller
  • Repetitive hardware and software maintenance
  • Administrative and management overhead
  • Cost of retaining hardware and software e.g. life cycle management
  • Factory defined limitation e.g. can’t do situation
  • Production downtime for maintenance work e.g. Dell Compellent maintenance

The following vendors provides various software defined storage in current market.

Software Only vendor

  • Atlantis Computing
  • DataCore Software
  • SANBOLIC
  • Nexenta
  • Maxta
  • CloudByte
  • VMware
  • Microsoft

Mainstream Storage vendor

  • EMC ViPR
  • HP StoreVirtual
  • Hitachi
  • IBM SmartCloud Virtual Storage Center
  • NetApp Data ONTAP

Storage Appliance vendor

  • Tintri
  • Nimble
  • Solidfire
  • Nutanix
  • Zadara Storage

Hyper Converged Appliance

  • Cisco (Starting price from $59K for Hyperflex systems+1 year support inclusive)
  • Nutanix
  • VCE (Starting price from $60K for RXRAIL systems+support)
  • Simplivity Corporation
  • Maxta
  • Pivot3 Inc.
  • Scale Computing Inc
  • EMC Corporation
  • VMware Inc

Ultimately, SDS should and will provide businesses will worry free management of storage without limitation of hardware. There are compelling use cases of software defined storage for an enterprise to adopt software defined storage.

Relavent Articles

Dell Compellent: A Poor Man’s SAN

I have been deploying Storage Area Network for almost ten years in my 16 years Information Technology career. I have deployed various traditional, software defined and converged SANs manufactured by a global vendor like IBM, EMC, NetApp, HP, Dell, etc. I was tasked with the deployment of Dell Compellent in my previous role for several clients. I was excited about the opportunities and paused after reading the documentation presented to me. I could not co-relate implementation of a SAN and expected outcome desired by clients. When over wild sales pitch is sold to businesses with high promises, then there will always be hidden risks that come with this sales pitch. Lesson number one never trusts someone blindly although they have a very decent track record, resellers are often after a quick sale and get out. Lesson number two make sure you know who to trust as your partner in the transition to have a new SAN. Decide what to procure based on your business case, ROI, workload analysis, capacity planning, lession learnt and outcome of requirement analysis. Consider current technology trend, where you are at now, a technology road map and where you want to be in future, e.g. Google Cloud, AWS or Azure. Capital investment can be the one off exercise these days before you pull the plug off on the on-premises infrastructure and fork-lift to Azure, Amazon or Google Cloud. Consider aligning technology stream with the business you do. I have written this article to share my own experience and disclose everything I learnt through my engagement on Dell Compellent deployment projects so that you can make a call by yourself. I will elaborate each feature of Dell Compellent and what exactly this feature does when you deploy a Compellent. FYI I have no beef with Dell. Let’s start now… “Marketing/sales pitch” vs “practical implication.”

Target Market: Small Business

Lets not go into detail, that will be a different topic for another day. Please read Dell’s business proposition “Ideally suited to smaller deployments across a variety of workloads, the SC Series products are easy to use and value optimized. We will continue to optimize the SC Series for value and server-attach.”

Management Interface: Dell Compellent Storage Center has a GUI designed to be accessible allegedly ease of use. Wizards offer few everyday tasks such as allocation, configuration, and administration functions. Compellent Storage Center monitoring tools provide very little insight on how storage backend is doing. You have to engage Dell remote support for diagnostic, and monitoring tools with alert and notification services. Storage center is not as granular as the competitor NetApp and EMC. Storage center has little information on storage performance, bottle neck and backend storage issues. Compellent is by design thin provisioned storage. There is no option in management center to assign as thick provisioned volume. IOPS and latency are calculated in volume and IOPS and latency are calculated in disks are far too different than real IOPS. You may see little IOPS in volume but click at drive level IOPS you will see storage controller is struggling to cope with the IOPS. Management center does not provide any clues who is generating this much IOPS.

Contact technical support they will say RAID scrub is killing your storage. Your standard request to tech support that stops the RAID scrub in a business hour. “You cannot do it” another classic reply by tech support. If you go through Compellent management center, you will find nothing that can schedule or stop RAID scrub.

Data Progression: In theory, Data Progression is an automated tiering technology that should have optimised the location of data, both on a schedule and on demand as prompted by a storage profile. Compellent’s tiering profiles streamline policy administration by assigning tier attributes based on the profile. On-demand data progression in a business hour will drive Compellent into crazy. If you are Citrix VDI mainstream than your workload is pretty much dead until data progression is complete.

A side effect of this technology is storage controller struggle to maintain on demand data progression and IO request at the same time hence there will be queue depth, and longer seek time in backend storage. In this situation, storage seek time is higher than normal.

Storage Profile: Storage profile in lay man’s terms is segregating expensive and cheap disk and profiling them in tier 1 (SSD RAID 10), tier 2 (15K Fibre Channel RAID 10, RAID 5, RAID 6) and tier 3 (7.2K SATA RAID 5, RAID 6). The storage profile determines how the system reads and writes data to disk for each volume as they are known in Compellent terms and how the data ages over time a feature called Data Progression. For example, random read request goes to tier 1 where you kept hot data, and a year old emails go to tier 3.

Storage Profiles supposed to allow the administrator to manage both writable blocks and replay blocks for a volume. It is fundamentally a tiering of storage in a controlled way. In theory, it supposed to be in a controlled environment. However, in reality, it does add extra workload to Dell Compellent controller. Let’s say you have tiered your storage according to your read and write intense IO. What happens when to READ and WRITE intense volume gets full?. Storage controller automatically triggers an on demand data progression from upper tier to lower tier to store data. Hence a WRITE intense IO is generated in lower tier what you wanted to avoid in the first place that’s why you profiled or tiered your storage. Mixing data progression with storage tiering defeats whole purpose of storage profiling.

Compellent Replay: Replay is essentially a storage snapshot in Dell terms. Dell Compellent Data Instant Replay software creates point-in-time copies called Replays. With Data Instant Replay Dell Compellent storage Replays at any time interval with minimal storage capacity. But here is the catch you will be most likely to run storage replay during the daily backup window. Backup generates lots of READ IOPS and Replays generate lots of READ and WRITE IOPS at the same time which is a daily backup window. Hence your backup is going to be dead slow. You will run out of the backup window and never be going to finish backup before the business hours. It will be a nightmare to fulfil data retention SLA and restore of any file systems and sensitive applications.

IOPS & Latency: Input/Output per second is a measurement unit of any hard disk and storage area network (SAN). This is a key performance matrix of a SAN regardless of manufacture, and this matrix remains unchanged. If you are to measure a SAN, this is where you begin. Never think that you have a bounce of virtual machines and it’s okay to buy SAN without IOPS consideration. There is the difference between a virtualised DHCP server and virtualised SQL server. A DHCP server may generate 20 IOPS but a SQL server can generate 5000 IOPS depends on what you are running on that SQL server. Every query you send to a SQL server or the application depends on the SQL server generate IOPS both read and write IOPS. For a Citrix XenApp and XenDesktop customer, you have to take into consideration that every time you launch a VDI session, open an word document, you generate IOPS, once you click save button on a word document, you generate write IOPS. Now you multiply the IOPS of each VDI session by the number of users, number of applications, number VDI and users inputs to estimate your real IOPS.

Now think about latency, in plain English, latency is the number of seconds or milli seconds you wait to retrieve information from a hard disk drive. This is calculated in round-trip between your request and the hard disk serve your request. Now you think millions of requests are bombarded on the storage area network. A SAN must sustain those requests and serve application requests, again it depends on what sort of workload you are running on a SAN. For example, file servers, Citrix profile, Citrix VDI, Exchange Server and SQL servers need low latency SAN.

In Dell Compellent, you may see volume IOPS e.g. 2000 but if you view disks hosting the same volume, then you might see 5000 IOPS. Then you must ask question how-come 5000-2000=3000 IOPS are generated automatically. Does Compellent has any tools to interrogate storage controller to see how additional workloads are generated? No it doesn’t. Your only bet is Dell support telling you the truth if you are lucky. The answer is automated RAID scrub is generating extra workloads on storage i.e. 3000 IOPS which could have been utilized for real workloads.

To co-relate this analysis with an all flash array storage, e.g. Dell Compellent, the SAN must be able to offer you the major benefits of a storage area network. If this storage cannot provide you low latency and high IO throughput for sensitive applications and workloads then you need to go back to drawing board or hire a consultant who can analyse your requirements and recommend you the options that match your need and budget. For further reading find Citrix validated solutions, storage best practices recommended by VMware and Microsoft. There are many tooling available in the market for you to analyse workload on applications, on a virtual or a physical infrastructure.

RAID Scrub: Data scrubbing is an error correction technique that uses a background task to inspect storage for errors periodically, and then correct detected errors using redundant data in the form of different checksums or copies of data. Data scrubbing reduces the likelihood that single correctable errors will accumulate, leading to reduced risks of uncorrectable errors.

In NetApp, you can schedule a RAID Scrub that suits your time and necessity however in Dell Compellent you cannot schedule a RAID Scrub through GUI or Command line. Dell technical support advised that this is an automated process takes places every day to correct RAID groups in Dell Compellent. There is a major side effect running automatic RAID scrub. RAID scrub will drive your storage to insane IOPS level, and latency will peak to high causing production volume to suffer and under perform. Performance of virtualisation will be degraded so badly that production environment will struggle to serve IO request. Dell advised that Dell can do nothing about RAID scrub because RAID scrub in SCOS operating systems is an automated process.

Compellent Multipathing: By implementing MPIO solution you eliminate any single point of failure in any physical path (s) and logical path(s) among any components such as adapters, cables, fabric switches, servers and storage. If one or more of these elements fails, causing the path to fail, multipathing logic uses an alternate path for I/O so that applications can still access their data. Each network interface card (in the iSCSI case) or HBA should be connected by using redundant switch infrastructures to provide continued access to storage in the event of a failure in a storage fabric component. This is the fundamental concept of any storage area network AKA SAN.

New generation SANs are integrated with multipath I/O (MPIO) support. Both Microsoft and VMware virtualisation architecture supports iSCSI, Fibre Channel and serial attached storage (SAS) SAN connectivity by establishing multiple sessions or connections to the storage array. Failover times may vary by storage vendor, and can be configured various way but the logic of MPIO remains unchanged.

New MPIO features in Windows Server include a Device Specific Module (DSM) designed to work with storage arrays that support the asymmetric logical unit access (ALUA) controller model (as defined in SPC-3), as well as storage arrays that follow the Active/Active controller model.

The Microsoft DSM provides the following load balancing policies. Microsoft load balance policies are generally dependent on the controller design (ALUA or true Active/Active) of the storage array attached to Windows-based computers.

Failover
Failback
Round-robin
Round-robin with a subset of paths
Dynamic Least Queue Depth
Weighted Path

VMware based systems also provide Fixed Path, Most Recently Used (MRU) and Round-Robin Configuration which is the most optimum configuration for VMware virtual infrastructure.

To explain ALUA in simple terms is that Server can see any LUN via both storage processors or Controller or NAS Head as active but only one of these storage processors “owns” the LUN. Both Storage Processor can view logical activities of storage using physical connection either via SAN switch to the server or via direct SAS cable connections. Hyper-v or vSphere ESXi server knows which processor owns which LUNs and sends traffic preferably directly to the owner. In case of controller or processor or NAS Head Failure Hyper-v or vSphere server automatically send traffic to an active processor without loss of any productivity. This is an essential feature of EMC, NetApp and HP products.

Let’s look at Dell Compellent now. Dell Compellent does not offer true Active/Active Controllers for any Storage. Dell Controllers Explained! Dell Verified Answer. Reference from Dell Forum….

“In the Compellent Architecture, both controllers are active. Failover is done at either the port or controller level depending on how the system was installed. Volumes are “owned” by a particular controller for mapping to servers. Changing the owning controller can be done – but it does take a volume down.”

I can confirm that this is exactly Dell Customer support advised me when I called them. Dell Compellent can take up to 60~90 seconds to failover from one controller to another. Which means entire virtual environment will go offline for a while and get back online. To update firmware or to replace a controller you have to bring everything down then bring everything back online which will cause a major outage and productivity loss for the entire organisation.

Multipathing options supported by the Host Utilities

Multipath I/O Overview

Multipathing Considerations

Dell Compellent is not an ALUA Storage Array

Performance Issue:  To identify Dell Compellent bottleneck for a virtualisation platform hosted in Compellent. Run the following in Windows perfmon in a virtual machine or a physical machine where a volume of Compellent storage is presented via HBA or iSCSI initiator. Use Windows perfmon, create a data collector set of the below attributes and generate a report using PAL tools. Extract seek time, latency, IOPS and queue depth in the Compellent storage. You will see a bottleneck in every area of storage you can expect. Read further on Windows Performance Monitoring Tools

\LogicalDisk\Avg. Disk Sec/Read

\LogicalDisk\Avg. Disk Sec/Write

\LogicalDisk\Disk Bytes/Sec

\LogicalDisk\Disk Reads/Sec

\LogicalDisk\Disk Writes/Sec

\LogicalDisk\Split IO/sec

\LogicalDisk\Disk Transfers/sec

Use the following Tools to analyse workloads and storage performance in your storage area network: 

Capacity planning & workload analysis tools

Multi-vendor storage performance and capacity monitoring

RVTools 

Windows Perfmon

PAL Analaysis Tools

Storage load generator / performance test tool

Dell EqualLogic Storage Management Pack Suite for SCOM

Monitoring EMC storage using SCOM 2012 SP1 with ESI Management Packs

IBM Storage Management Pack for Microsoft System Center Operations Manager

Cost Compare:

The cost of each gigabyte of storage is declining rapidly in every segment of the market. Enterprise storage today costs what desktop storage did less than a decade ago. So why are your overall costs increasing when buying storage? Let’s make it simple! Ask yourself questions?

How much will the storage cost? How much will the SAN cost to implement? How much will the SAN cost to operate? Now use the below tools to calculate the real cost of the owing black box?

Amazon EBS Pricing

Google Cloud Platform Pricing Calculator

Azure Storage Pricing

IBM TCO Calculator

vSAN Hybrid TCO and Sizing Calculator

HPE Business Value Calculator

Microsoft TCO Calculator

So what will you be looking in a SAN? 

  • Lower TCO
  • Storage Performance
  • Scale-to-Fit
  • Quality of Service
  • Uncompromised Availability and uptime
  • Cloud Ready
  • Reduction of Data (de-duplication)
  • Reduction of backup
  • Analytics and automation
  • Reduction of Data Centre footprint 

Summary: Dell Compellent makes a compelling argument for all-flash performance tiers. Yes, this argument is in sales pitch not in reality. A price conscious poor man who needs just any SAN and has a lower IO environment can have Compellent. For mainstream enterprise storage, Dell Compellent is a bad experience and can bring disaster to corporate Storage Area Network (SAN).

I had no doubt when Compellent introduced all flash arrays it was innovative but Compellent’s best days are gone. Just shop around, you will find better all-flash, converged, hybrid and virtual arrays which are built on better software, controllers and SSDs. There are flash arrays in the market which run clever codes and algorithm within the software to produce high IO, low latency and performance for sensitive applications.

Related Articles: 

Pro Tips For Storage Performance Testing

Storage Top 10 Best Practices

SQLIO download page

SQLIOSim tool KB article

SQL Server Storage Engine Team Blog

SQL Server I/O Basics

SQL Server I/O Basics – Chapter 2

Predeployment I/O Best Practices

Disk Partition Alignment Best Practices for SQL Server

EMC Symmetrix DMX-4 Enterprise Flash Drives with Microsoft SQL Server Databases

Implementing EMC CLARiiON CX4 with Enterprise Flash Drives for Microsoft SQL Server 2008 Databases

Microsoft. “Lab Validation Report: Microsoft Windows Server 2012 with Hyper-V and Exchange 2013

Microsoft TechNet. “Exchange 2013 Virtualization.”

Microsoft TechNet. “Failover Clustering Hardware Requirements and Storage Options.” Aug 2012.

Dell Compellent Storage to be discontinued after Dell-EMC merger

DELL is buying EMC. This is an old news. You already know this. There are many business reasons Dell is buying EMC. EMC is the number one storage vendor and a big cat of NASDAQ. One key business justification is to get into Enterprise market with enterprise class product lines and second big reason is break into cloud market utilising dominant presence of EMC. Have you rationalised your opinion on what Dell storage product line likely to be once merger is complete. There are many argument in for and against of various combination of storage line Dell will come up. Let’s look at current product lines of Dell and EMC.

Dell Current Product Line:

  • Network Attached storage based on Dell 2U rack servers.
  • Direct Attached Storage
  • iSCSI and FCoE SAN solution such as PowerVault MD, EqualLogic, Compellent

EMC Product Line:

  • EMC XtremIO – the XtremIO all-flash array—ideal for virtual desktop infrastructure (VDI), virtual server, and database
  • EMC VMAX enterprise class storage- Mission critical storage for hyper consolidation and delivering IT as a service.
  • EMC VNX/VNXe – hybrid flash storage platform, optimized for virtual applications.

Software Defined Storage

Dell

  • Software defined storage such as Dell XC Series powered by Nutanix

EMC

  • EMC Isilon – High-performance, clustered network-attached storage (NAS) that scales to your performance and capacity requirements.
  • EMC ScaleIO – Hyper-converged solution that uses your existing servers, and turns them into a software defined SAN with massive scalability, 10X better performance and 60% lower cost than traditional storage.
  • EMC Elastic Cloud Storage (ECS) – Cloud-scale, geo-federated namespace, multi-tenant security and in-place analytics ECS is the universal platform
  • EMC ViPR Controller – deliver automation and management insights from your multivendor storage.
  • EMC Service Assurance Suite – Service Assurance Suite delivers service-aware software defined network management that optimizes your physical and virtual networks, increases operational efficiency by ensuring SLA’s, and reduces cost by maximizing resources.
  • EMC ViPR SRM – optimize your multivendor block, file & object storage tiers to application service levels you’ll maximize resources, reduce costs and improve your return on investment.

Other Partnership and Products of EMC

EMC Vblock Systems – VCE is a technology partnership which EMC plays major role to deliver converged cloud solutions for midrange to enterprise client. Converged Infrastructure technology that provide virtualization, server, network, storage and backup, VCE Converged Solutions simplify all aspects of IT.

EMC Hybrid Cloud- Federation Enterprise Hybrid Cloud for delivering IT-as-a-Service. With thousands of engineering hours, the Federation brings together best-in-class components from EMC, VCE, and VMware to create a fully integrated, enterprise-ready solution.

VMware Partnerships-EMC Corp plans to keep its majority stake in VMware Inc. EMC, which owns about 80% of VMware, bought the company in 2004 for $700 million. VMware accounted for about 22 percent of EMC’s revenue of $23.2 billion in 2013. EMC and VMware share a cloud vision. Through joint product development, solutions, and services, EMC is the number one choice for VMware customers for storage, backup, security, and management solutions.

RSA Information Security division- RSA info security offers data protection and identity management.

Pivotal- EMC and VMware partnership to manufacture software and big data solutions.

Virtustream- EMC and VMware joint $1.2B acquisition of this brand to provide public cloud services.

Dell to discontinue Compellent after merger–make sense

There are too many eggs on the busket already. Would Dell continue to sell identical products in different name or stream line all products. Dell is after streamlining all products. It is well known by Dell loyal customer that EqualLogic will disappear from Dell product line at 2018. We learnt that in Dell partner’s conference. Then question will remain what will happen to Compellent? In current market place, VNX directly compete with Dell Compellent. But VNX has more customer base than Compellent. VNX is in market for almost 20 years and still growing fast. Compellent is in new shape and in market with SC series product line. But Compellent has frustrated its customer with poor performance and poor customer support. A very poor explanation and guidelines from Dell presales team on how to align Dell storage with business requirement.

Dell can offer customer will both VNX and Compellent knowing Compellent did not work from the beginning or Dell streamline its product and kill Compellent all together. Then promote VNX as it worked past 20 years and has a proven track record. Killing Compellent will disturb few already unhappy customer who simply wanted cheap SATA disks. But killing VNX will disturb wide range of customers and annoy them once and for all. Consequence of that would be losing customers to HP and NetApp which dell desperately wants to avoid and gain control of storage market. This way Dell-EMC will retain undisputed title of EMC as a number one storage vendor. This make sense for any non IT savvy walking on the street. I am certain and believe that Dell will discontinue Compellent serries all together.  Protecting $67 billion dollar acquisition of EMC is more important than protecting $960 million acquisition of Compellent. It would obviously make sense for Michael Dell to kill Compellent and promote VNX as a sole mid range storage.

References:

Dell Compellent: A Poor Man’s SAN

EMC plans to keep stake in VMware, despite investor pressure: source

EMC-VMware Alliance

EMC Cloud

Dell Product Lines

EMC Product Lines

VCE Converged Systems

Dell buying EMC

Dell-EMC: What Storage Customers Should Do

Veeam integrate with EMC and NetApp Storage Snapshots!

Taking a VMware snapshots and Hyper-v checkpoint can produce a serious workload on VM performance, and it can take considerable effort by sys admin to overcome this technical challenge and meet the required service level agreement. Most Veeam user will run their backup and replication after hours considering impact to the production environment, but this can’t be your only backup solution. What if storage itself goes down, or gets corrupted? Even with storage-based replication, you need to take your data out of the single fault domain. This is why many customers prefer to additionally make true backups stored on different storage. Never to store production and backup on to a same storage.

Veeam1

Source: Veeam

Now you can take advantage of storage snapshot. Veeam decided to work with storage vendor such as EMC and NetApp to integrate production storage, leveraging storage snapshot functionality to reduce the impact on the environment from snapshot/checkpoint removal during backup and replication.

Supported Storage

  • EMC VNX/VNXe
  • NetApp FAS
  • NetApp FlexArray (V-Series)
  • NetApp Data ONTAP Edge VSA
  • HP 3PAR StoreServ
  • HP StoreVirtual
  • HP StoreVirtual VSA
  • IBM N series

Unsupported Storage

  • Dell Compellent

NOTE: My own experience with HP StoreVirtual and HP 3PAR are awful. I had to remove HP StoreVirtual from production store and introduce other fibre channel to cope with workload. Even though Veeam tested snapshot mechanism with HP, I would recommend avoid HP StoreVirtual if you have high IO workload.

Benefits

Veeam suggest that you can get lower RPOs and lower RTOs with Backup from Storage Snapshots and Veeam Explorer for Storage Snapshots.

Veeam and EMC together allow you to:

  • Minimize impact on production VMs
  • Rapidly create backups from EMC VNX or VNXe storage snapshots up to 20 times faster than the competition
  • Easily recover individual items in two minutes or less, without staging or intermediate steps

As a result of integrating Veeam with EMC, you can backup 20 times faster and restore faster using Veeam Explorer. Hence users can achieve much lower RPOs (recovery point objectives) and lower RTOs (recovery time objectives) with minimal impact on production VMs.

How it works

Veeam Backup & Replication works with EMC and NetApp storage, along with VMware to create backups and replicas from storage snapshots in the following way.

Veeam2

Source: Veeam

The backup and replication job:

  1. Analyzes which VMs in the job have disks on supported storage.
  2. Triggers a vSphere snapshot for all VMs located on the same storage volume. (As a part of a vSphere snapshot, Veeam’s application-aware processing of each VM is performed normally.)
  3. Triggers a snapshot of said storage volume once all VM snapshots have been created.
  4. Retrieves the CBT information for VM snapshots created on step 2.
  5. Immediately triggers the removal of the vSphere snapshots on the production VMs.
  6. Mounts the storage snapshot to one of the backup proxies connected into the storage fabric.
  7. Reads new and changed virtual disk data blocks directly from the storage snapshot and transports them to the backup repository or replica VM.
  8. Triggers the removal storage snapshot once all VMs have been backed up.

VMs run off snapshots for the shortest possible time (Subject to storage array- EMC works better), while jobs obtain data from VM snapshot files preserved in the storage snapshot. As the result, VM snapshots do not get a chance to grow large and can be committed very quickly without overloading production storage with extended merge procedure, as is the case with classic techniques for backing up from VM snapshots.

Integration with EMC storage will bring great benefit to customers who wants to take advantage of their storage array. Veeam Availability Suite v9 will provide the chance to reduce IO on to your storage array and bring your SLA under control.

References:

Backup from storage snapshots

Integration with emc storage snapshot

Veeam integrates with emc snapshots

New Veeam availability suite version 9

 

 

 

Gartner’s verdict on mid-range and enterprise class storage arrays

Previously I wrote an article on how to select a SAN based on your requirement. Let’s learn what Gartner’s verdict on Storage. Gartner scores storage arrays in mid-range and enterprise class storage. Here are details of Gartner score.

Mid-Range Storage

Mid-range storage arrays are scored on manageability, Reliability and Availability (RAS), performance, snapshot and replication, scalability, the ecosystem, multi-tenancy and security, and storage efficiency.

mid1

Figure: Product Rating

mid2

Figure: Storage Capabilities

mid3

Figure: Product Capabilities

mid4

Figure: Total Score

Enterprise Class Storage

Enterprise class storage is scored on performance, reliability, scalability, serviceability, manageability, RAS, snapshot and replication, ecosystem, multi-tenancy, security, and storage efficiency. Vendor reputation are more important in this criteria. Product types are clustered, scale-out, scale-up, high-end (monolithic) arrays and federated architectures. EMC, Hitachi, HP, Huawei, Fujitsu, DDN, and Oracle arrays can all cluster across more than 2 controllers. These vendors are providing functionality, performance, RAS and scalability to be considered in this class.

ENT1

Figure: Product Ratings (Source: Gartner)

Where does Dell Compellent Stand?

There are known disadvantages in Dell Compellent storage array, users with more than two nodes must carefully plan firmware upgrades during a time of low I/O activity or during periods of planned downtime. Even though Dell Compellent advertised as flash cached, Read SSD and Write SSD with storage tiering, snapshot. In realty Dell Compellent does its own thing in background which most customer isn’t aware of. Dell Compellent run RAID scrub every day whether you like it or not which generate huge IOPS in all tiered arrays which are both SSD and SATA disks. You will experience poor IO performance during RAID scrub. When Write SSD is full Compellent controller automatically trigger an on demand storage tiering during business hour and forcing data to be written permanently in tier 3 disks which will literally kill virtualization, VDI and file systems. Storage tiering and RAID scrub will send storage latency off the roof. If you are big virtualization and VDI shop than you are left with no option but to experience this poor performance and let RAID scrub and tiering finish at snail pace. If you have terabytes of data to be backed up every night you will experience extended backup window, un-achievable RPO and RTO regardless of change block tracking (CBT) enabled in backup products.

If you are one of Compellent customer wondering why Garner didn’t include Dell Compellent in Enterprise class. Now you know why Dell Compellent is excluded in enterprise class matrix as Dell Compellent doesn’t fit into the functionality and capability requirement to be considered as enterprise class. There is another factor that may worry existing Dell EqualLogic customer as there is no direct migration path and upgrade path have been communicated with on premises storage customers once OEM relationship between Dell and EMC ends. Dell pro-support and partner channel confirms that Dell will no longer sell SAS drive which means IO intense array will lose storage performance. These situations put users of co-branded Dell:EMC CX systems in the difficult position of having to choose between changing changing storage system technologies or changing storage vendor all together.

Buying a SAN? How to select a SAN for your business?

A storage area network (SAN) is any high-performance network whose primary purpose is to enable storage devices to communicate with computer systems and with each other. With a SAN, the concept of a single host computer that owns data or storage isn’t meaningful. A SAN moves storage resources off the common user network and reorganizes them into an independent, high-performance network. This allows each server to access shared storage as if it were a drive directly attached to the server. When a host wants to access a storage device on the SAN, it sends out a block-based access request for the storage device.

A storage-area network is typically assembled using three principle components: cabling, host bus adapters (HBAs) and switches. Each switch and storage system on the SAN must be interconnected and the physical interconnections must support bandwidth levels that can adequately handle peak data activities.

Good SAN

A good provides the following functionality to the business.

Highly availability: A single SAN connecting all computers to all storage puts a lot of enterprise information accessibility eggs into one basket. The SAN had better be pretty indestructible or the enterprise could literally be out of business. A good SAN implementation will have built-in protection against just about any kind of failure imaginable. As we will see in later chapters, this means that not only must the links and switches composing the SAN infrastructure be able to survive component failures, but the storage devices, their interfaces to the SAN, and the computers themselves must all have built-in strategies for surviving and recovering from failures as well.

Performance:

If a SAN interconnects a lot of computers and a lot of storage, it had better be able to deliver the performance they all need to do their respective jobs simultaneously. A good SAN delivers both high data transfer rates and low I/O request latency. Moreover, the SAN’s performance must be able to grow as the organization’s information storage and processing needs grow. As with other enterprise networks, it just isn’t practical to replace a SAN very often.

On the positive side, a SAN that does scale provides an extra application performance boost by separating high-volume I/O traffic from client/server message traffic, giving each a path that is optimal for its characteristics and eliminating cross talk between them.

The investment required to implement a SAN is high, both in terms of direct capital cost and in terms of the time and energy required to learn the technology and to design, deploy, tune, and manage the SAN. Any well-managed enterprise will do a cost-benefit analysis before deciding to implement storage networking. The results of such an analysis will almost certainly indicate that the biggest payback comes from using a SAN to connect the enterprise’s most important data to the computers that run its most critical applications.

But its most critical data is the data an enterprise can least afford to be without. Together, the natural desire for maximum return on investment and the criticality of operational data lead to Rule 1 of storage networking.

Great SAN

A great SAN provides additional business benefits plus additional features depending on products and manufacturer. The features of storage networking, such as universal connectivity, high availability, high performance, and advanced function, and the benefits of storage networking that support larger organizational goals, such as reduced cost and improved quality of service.

  • SAN connectivity enables the grouping of computers into cooperative clusters that can recover quickly from equipment or application failures and allow data processing to continue 24 hours a day, every day of the year.
  • With long-distance storage networking, 24 × 7 access to important data can be extended across metropolitan areas and indeed, with some implementations, around the world. Not only does this help protect access to information against disasters; it can also keep primary data close to where it’s used on a round-the-clock basis.
  • SANs remove high-intensity I/O traffic from the LAN used to service clients. This can sharply reduce the occurrence of unpredictable, long application response times, enabling new applications to be implemented or allowing existing distributed applications to evolve in ways that would not be possible if the LAN were also carting I/O traffic.
  • A dedicated backup server on a SAN can make more frequent backups possible because it reduces the impact of backup on application servers to almost nothing. More frequent backups means more up-to-date restores that require less time to execute.

Replication and disaster recovery

With so much data stored on a SAN, your client will likely want you to build disaster recovery into the system. SANs can be set up to automatically mirror data to another site, which could be a fail safe SAN a few meters away or a disaster recovery (DR) site hundreds or thousands of miles away.

If your client wants to build mirroring into the storage area network design, one of the first considerations is whether to replicate synchronously or asynchronously. Synchronous mirroring means that as data is written to the primary SAN, each change is sent to the secondary and must be acknowledged before the next write can happen.

The alternative is to asynchronously mirror changes to the secondary site. You can configure this replication to happen as quickly as every second, or every few minutes or hours, Schulz said. While this means that your client could permanently lose some data, if the primary SAN goes down before it has a chance to copy its data to the secondary, your client should make calculations based on its recovery point objective (RPO) to determine how often it needs to mirror.

Security

With several servers able to share the same physical hardware, it should be no surprise that security plays an important role in a storage area network design. Your client will want to know that servers can only access data if they’re specifically allowed to. If your client is using iSCSI, which runs on a standard Ethernet network, it’s also crucial to make sure outside parties won’t be able to hack into the network and have raw access to the SAN.

Capacity and scalability

A good storage area network design should not only accommodate your client’s current storage needs, but it should also be scalable so that your client can upgrade the SAN as needed throughout the expected lifespan of the system. Because a SAN’s switch connects storage devices on one side and servers on the other, its number of ports can affect both storage capacity and speed, Schulz said. By allowing enough ports to support multiple, simultaneous connections to each server, switches can multiply the bandwidth to servers. On the storage device side, you should make sure you have enough ports for redundant connections to existing storage units, as well as units your client may want to add later.

Uptime and availability

Because several servers will rely on a SAN for all of their data, it’s important to make the system very reliable and eliminate any single points of failure. Most SAN hardware vendors offer redundancy within each unit — like dual power supplies, internal controllers and emergency batteries — but you should make sure that redundancy extends all the way to the server. Availability and redundancy can be extended to multiple systems and cross datacentre which comes with cost benefit analysis and specific business requirement. If your business drives to you to have zero downtime policy then data should be replicated to a disaster recovery sites using identical SAN as production. Then use appropriate software to manage those replicated SAN.

Software and Hardware Capability

A great SAN management software deliver all the capabilities of SAN hardware to the devices connected to the SAN. It’s very reasonable to expect to share a SAN-attached tape drive among several servers because tape drives are expensive and they’re only actually in use while back-ups are occurring. If a tape drive is connected to computers through a SAN, different computers could use it at different times. All the computers get backed up. The tape drive investment is used efficiently, and capital expenditure stays low.

A SAN provide fully redundant, high performance and highly available hardware, software for application and business data to compute resources. Intelligent storage also provide data movement capabilities between devices.

Best OR Cheap

No vendor has ever developed all the components required to build a complete SAN but most vendors are engaged in partnerships to qualify and offer complete SANs consisting of the partner’s products.

Best-in-class SAN provides totally different performance and attributes to business. A cheap SAN would provide a SAN using existing Ethernet network however you should ask yourself following questions and find answers to determine what you need? Best or cheap?

  1. Has this SAN capable of delivering business benefits?
  2. Has this SAN capable of managing your corporate workloads?
  3. Are you getting correct I/O for your workloads?
  4. Are you getting correct performance matrix for your application, file systems and virtual infrastructure?
  5. Are you getting value for money?
  6. Do you have a growth potential?
  7. Would your next data migration and software upgrade be seamless?
  8. Is this SAN a heterogeneous solutions for you?

Storage as a Service vs on-premises

There are many vendors who provides storage as a service with lucrative pricing model. However you should consider the following before choosing storage as a service.

  1. Does this vendor a partner of recognised storage manufacturer?
  2. Does this vendor have certified and experienced engineering team to look after your data?
  3. Does this vendor provide 24x7x365 support?
  4. Does this vendor provide true storage tiering?
  5. What is geographic distance between storage as a service provider’s data center and your infrastructure and how much WAN connectivity would cost you?
  6. What would be storage latency and I/O?
  7. Are you buying one off capacity or long term corporate storage solution?

If answers of these questions favour your business then I would recommend you buy storage as a service otherwise on premises is best for you.

NAS OR FC SAN OR iSCSI SAN OR Unified Storage

A NAS device provides file access to clients to which it connects using file access protocols (primarily CIFS and NFS) transported on Ethernet and TCP/IP.

A FC SAN device is a block-access (i.e. it is a disk or it emulates one or more disks) that connects to its clients using Fibre Channel and a block data access protocol such as SCSI.

An iSCSI, which stands for Internet Small Computer System Interface, works on top of the Transport Control Protocol (TCP) and allows the SCSI command to be sent end-to-end over local-area networks (LANs), wide-area networks (WANs) or the Internet.

You have to know your business before you can answer the question NAS/FC SAN/iSCSI SAN or Unified? Would you like to maximise your benefits from same investment well you know the answer you are looking for unified storage solutions like NetApp or EMC ISILON. If you are looking for enterprise class high performance storage, isolate your Ethernet from storage traffic, reduce backup time, minimise RPO and RTO then FC SAN is best for you example EMC VNX and NetApp OnCommand Cluster. If your intention is to use existing Ethernet and have a shared storage then you are looking for iSCSI SAN example Nimble storage or Dell SC series storage. But having said that you also needs to consider your structured corporate data, unstructured corporate data and application performance before making a judgement call.

Decision Making Process

Let’s make a decision matrix as follows. Just fill the blanks and see the outcome.

Workloads I/O Capacity Requirement (in TB) Storage Protocol

(FC, iSCSI, NFS, CIFS)

Virtualization
Unstructured Data
Structured Data
Messaging Systems
Application virtualization
Collaboration application
Business Application

Functionality Matrix

Option Rating Requirement (1=high 3=Medium 5=low )
Redundancy
Uptime
Capacity
Data movement
Management

Risk Assessment

Risk Type Rating (Low, Medium, High)
Loss of productivity
Loss of redundancy
Reduced Capacity
Uptime
Limited upgrade capacity
Disruptive migration path

Service Data – SLA

Service Type SLA Target
Hardware Replacement
Uptime
Vendor Support

Rate storage via Gartner Magic Quadrant. Gartner magic quadrant leaders are (as of October 2015):

  1. EMC
  2. HP
  3. Hitachi
  4. Dell
  5. NetApp
  6. IBM
  7. Nimble Storage

To make your decision easy select a storage that enables you to cost effective way manage large and rapidly growing data. A storage that is built for agility, simplicity and provide both tiered storage approach for specialized needs and the ability to unify all digital contents into a single high performance and highly scalable shared pool of storage. A storage that accelerate productivity and reduce capital and operational expenditures, while seamlessly scaling storage with the growth of mission critical data.