Midrange SANs with high-end features from Compellent, Xiotech

The system I received for testing included one FC bay with 16 146GB 10K U320 drives (SBOD), one SATA bay with 12 400GB SATA drives, two storage controllers, and one ICON (Intelligent CONtroller) management module.

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Management is done via the ICON Web interface, along with a few tasks performed through the DCN (Dimensional Controller Nodes) storage controllers’ Web interfaces. Xiotech requires only one DCN but recommends a dual-path, dual-controller setup for redundancy; only one ICON is necessary, no matter how many DCN controllers there are.

As with Compellent, Magnitude’s wizards perform most configuration tasks. The ICON management interface has separate log-ins for each type of storage -- the high-performance bay has one log-in, and the SATA bay has another. This separation can complicate some tasks, such as migrating a volume from the FC shelf to the SATA shelf, because you have to change log-ins to perform some of the necessary tasks. The multiple log-ins do allow granular management, but the Compellent system does the same in a more straightforward fashion by giving the overall manager delegation of any volume without requiring you to switch log-ins.

Moving from one Magnitude storage tier to another, or from one RAID level to another, involves creating a second virtual disk, using the copy and mirror procedure to copy the first partition, and then breaking the mirror and attaching the second copy to the server in place of the first. This procedure is done fairly easily through the UI -- and without interrupting access to data. It is, however, a more involved process than with Compellent.

Expanding an existing virtual disk is fairly straightforward, as is setting up the snapshots and replication features. The Magnitude management interface is a multiple-tab affair; finding the necessary screen to configure any given feature by browsing through the tabs was usually easy.

Magnitude’s SAN map shows a physical map of the SAN, using a block diagram. It has excellent reporting tools that show environmental statistics, I/O by vdisk or RAID array, by drive shelf, or by physical or logical device. It also has a useful built-in Active Watch tool that will report any crossing of performance thresholds via e-mail or SNMP alarms.

Tracking Performance
I ran Intel IOmeter tests on both systems’ first- and second-tier storage volumes and found that Compellent Storage Center consistently ran about 20 percent faster than the Xiotech Magnitude system on both high-performance and SATA volumes. Tests were run from the same server, using the same HBA, with newly created volumes for each test. Coupled with the Compellent system’s higher total capacity -- it supports unlimited capacity, compared with Xiotech’s 19.2TB limit -- these performance numbers give Compellent a stronger leg to stand on.

That’s not to say that the Magnitude 3D 3000e System is a bad choice; it’s a well-engineered system that would look good in comparison to most other midtier SAN systems on the market. The Compellent system, however, is more mature and shows it. It offers automatic data migration, a cleaner, easier-to-use interface, and higher performance, all for about the same price per gigabyte.