When Storage Center 4.0 arrived in our lab, we had to ask: "Who is Compellent?" Founded in 2002 by a group of storage and virtualization executives, Compellent targets small and midsize businesses that want high-end SAN features and low-end management hassles.
The best audience for Storage Center 4.0 consists of midsize organizations whose storage needs generally scale up through about 50 TB. The company claims it can scale way beyond 50 TB for the enterprise market. Compellent increasingly is competing with the likes of EMC's CX300 series Clariion line as well as NetApp's FAS 2000 and 3000 series storage area network, says Compellent senior marketing manager Bob Fine.
Out of the box, Storage Center has an excellent tiered storage system for a SAN fit for a small or midsize business. What's the big deal about tiered storage? According to Compellent's own research, 80% of data ends up just sitting on file shares, never to be accessed again, after 60 days. EMC cites a similar statistic. Fibre Channel storage is expensive, so to the degree that companies can shift old data to low-cost, secondary storage to save money, they should do so.
Compellent makes this possible with a built-in tiered storage technology. The system defines Tier 1 storage as 15,000-rpm Fibre Channel drives, Tier 2 as 10,000-rpm FC drives, and Tier 3 as 7,000-rpm SATA drives.
Once we defined our storage volumes and attached them to our lab file server, we implemented a default policy in which a file that wasn't touched for three days was moved to Tier 2. If that same file was not touched for another three days, it was moved down to the el cheapo SATA storage tier.
The functionality worked well: Six days after loading our storage array, our data was on the SATA volume. Storage Center also can move older data back to the higher tiers if it's repeatedly accessed.
We then set our sights on an add-on component called FastTrack. The FastTrack feature moves frequently accessed data to tracks on the outer perimeter of the spindle, where the drive head can seek data more quickly, improving overall disk performance. Compellent says that FastTrack is unique in that it moves individual blocks to outer tracks while competitors can move only entire volumes.
Compellent says its lab testing demonstrates improved seek times and disk performance of up to 30%. We couldn't vet this claim because our simple file system was already running on the fastest disk in the array. We weren't able to see a difference in seek times with FastTrack either on or off simply by moving files between systems on and off the SAN. That said, if the FastTrack feature works as advertised, applications that rely on a large amount of disk I/O are sure to benefit from the functionality.