Midrange SANs master high-end features
Compellent, iQstor, and Xiotech combine sophisticated enterprise capabilities with amazing ease
The same instant replay functionality can be used for servers. Once a boot volume is set up and the operating system is installed for a server, a second bootable volume can be created, and the only additional space used is that which stores the files that are different. For Linux this might amount to a few configuration files, and even for Windows it doesn’t amount to much except for the Windows swap file. This means that you could have several hundred servers booting from one main OS image, and each would maintain only the files that are different. It also means that rolling out patches and updates can be greatly simplified, since only the main image needs to be updated, and the others recloned. Unfortunately, there isn’t yet a way to push changes in the main image out to the clones.
The Compellent Storage Center offers superb ease of use and the widest feature set available in the middle range, without charging a premium price. The wizard-based configuration means that even administrators in small shops who don’t have time to go to storage administration training will be able to set up and use all the sophisticated features available. And the instant replay and automated migration features mean that you can get the best performance where needed and make full use of inexpensive SATA-based storage without any additional effort.
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The iQstor system offers less flexibility than the Compellent and Xiotech systems because it doesn't allow a RAID set to be changed or resized once created. The virtual disks in a RAID set can be changed, but not the underlying RAID level.
The system I tested included 15 73GB 4Gbps FC drives. The same enclosure supports a wide range of FC drives as well as SATA drives. The iQstor unit came in at the lowest price among the three systems tested. And though it also arrived with the lowest storage capacity, adding more drives or including higher capacity drives would not push the price from $21,195 to anywhere near the $50,000 or more of the other two. As with the Compellent and Xiotech systems, iQstor supports active-active controllers for full redundancy, and it's easy to add more FC or SATA enclosures to boost total capacity.