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 arrays are scored on manageability, Reliability and Availability (RAS), performance, snapshot and replication, scalability, the ecosystem, multi-tenancy and security, and storage efficiency.
Figure: Product Rating
Figure: Storage Capabilities
Figure: Product Capabilities
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.
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.