Midrange SANs master high-end features
Compellent, iQstor, and Xiotech combine sophisticated enterprise capabilities with amazing ease
The Magnitude 3D supports ILM-style data migration through host-based software, which uses agents on each server to identify data that can be migrated from tier one to tier two or three. This is not as transparent as data migration in Compellent, which is handled in the controller with no server agents or additional load on the servers required. Nevertheless Xiotech provides some of the same functionality, albeit with more setup required.
The TimeScale appliance enables a number of features not available from Compellent. It provides compression, encryption, and deduplication of data sent over the WAN link, which both secures transmitted data and optimizes the use of the link. TimeScale can replicate data to other systems from other storage vendors, even allowing the use of server-attached storage. This means that a single TimeScale box can facilitate replication across the enterprise, between a widely disparate variety of storage systems. TimeScale also supports bandwidth limiting by connection, allowing the administrator to control both the amount of bandwidth consumed by remote replication or CDP and also the amount of server utilization for local replication. Server utilization can be a significant factor, because heterogeneous replication routes data through the server that the storage is attached to, rather than bypassing the server and routing data from one SAN device to another. This is the only way to make use of non-SAN storage, but it can introduce fairly heavy loads on the server, depending on the amount of data being replicated.
Creating asynchronous replicas (on a second Xiotech SAN system) over the WAN using the TimeScale appliance is straightforward and fairly simple, although not quite as simple as the five-click process in Compellent. Given the additional complexity introduced by enabling the use of other SAN devices and server-attached storage, this is not unexpected, and in fact it makes the smoothness of the Xiotech process all the more admirable.
TimeScale also allows the administrator to schedule and create an unlimited number of snapshots for data or system recovery, using either virtual snapshots to reduce the storage footprint or full replicas of the original data. Snapshots can be one to many, many to one, or many to many, allowing multiple snapshots to be created in different places from a single original, or allowing multiple originals to be consolidated into a single storage system.
The Xiotech system with the TimeScale appliance offers a couple of features not available from Compellent, including the SSD drives and replication and mirroring with heterogeneous devices. It doesn’t have hardware-based ILM, and it's not quite as easy to use as the Compellent system, but it's an excellent choice for administrators aiming to reuse existing storage assets.
The fat middle
All three of the systems reviewed here will provide excellent service in a small to midlevel enterprise environment. They are inexpensive enough to be good starter systems, yet expandable enough to grow with a company’s data needs. And all combine good usability and strong performance.
The iQstor iQ2880 has a more limited feature set than the other two, but still enough for most purposes, and it comes at a very low price. The Xiotech Magnitude 3D system offers sophisticated features at a reasonable price, including the highest possible performance (thanks to the solid state disk option) and excellent replication functions that support any SAN or server attached storage, even from other vendors.
The Compellent Storage Center offers the greatest ease of use, as well as automated data migration capabilities, at a great price. In fact, Compellent's level of maturity, both in feature set and ease of use, places it alone at the pinnacle of midrange systems and even compares favorably with top-tier systems. That said, if you don't need automated data migration, the iQstor is the most affordable way to start. And Xiotech should get a close look from any shop looking for a SAN that plays well with existing storage.
Read more about storage in InfoWorld's Storage Channel.