Many companies use SATA drives for storage because they hold a lot of data and because they're much cheaper than SAS and Fibre Channel alternatives. However, SATA drives are historically unreliable and don't perform as well as Fibre Channel or SAS drives. One of the biggest problems with SATA drives is the possibility of silent data corruption -- the drive forwards incorrect data but doesn't generate an error message to alert you of the problem.
DataDirect Networks (DDN) addresses this problem with its new SATAssure technology, which is embedded in DDN's storage controller, the Silicon Storage Appliance (S2A), as part of DirectOS 3.08. According to the company, SATAssure lets the S2A storage controller manage a large pool of SATA drives, while still providing data integrity, reliability, and availability.
One of the ways that SATAssure ensures data integrity and reliability is that it validates the data coming from the SATA drive on every single read operation. SATAssure ensures data availability because it can detect and correct problems such as silent data corruption on the fly, without interfering with the drive's performance. Traditionally, if a drive fails and needs to be rebuilt, performance of the array goes down during the rebuild period. In addition, the rebuild time can be quite lengthy.
To prevent downtime, the S2A storage controller continues journaling a SATA drive's write operations even when you take the drive offline temporarily to perform recovery operations. When you bring the drive back online, you only have to do a partial rebuild of the journal contents, rather than rebuild the entire contents of the drive.
For more information about DDN's S2A storage controller and the SATAssure technology, visit the company's Web site.
