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All in one box
One of the more interesting developments in secondary storage is the trend toward putting primary and secondary disks in the same array. "It's absolutely happening," says Sun's Wood of mixing primary and secondary storage in a single box. "There's one thing to manage--one consistent interface, not two."
HDS allows the mixing of FC and SATA disks in one Lightning subsystem, and EMC and HP have similar offerings. "The idea of being able to tier within an array is interesting," says ESG's Hurley. "You're not forcing people to buy two separate solutions." She also cites startup Compellent's Storage Center array which, along with an innovative system of allocating disk only when applications write data, allows mixing of FC, iSCSI and SATA disks. Moving data among unlike storage devices can still be difficult, so having different classes of storage in a single box makes tiering storage far easier.
At least one company is taking the mixed box concept a step further, according to Hurley. She says that Pillar Data, although it hasn't announced a product yet, is rumored to be working on technology that tiers storage on a single disk. Pillar's technology is based on the fact that data on the outside edge of a disk can be accessed faster than the data on the inner sections. "They've actually figured out how to tier at the component level," says Hurley.
Successful secondary storage implementations start with a solid plan. Forsythe's Geis says you need to have a good grasp on the driving force behind your secondary storage plans: "Is it cost? Is it management?" He adds that other issues must be considered, too, such as how the secondary storage will integrate with the current infrastructure and management system and to ensure that it works the backup and recovery already in place.
Secondary storage has a better chance of being a cost or time saving factor if the software associated with it is policy-driven and as automated as possible. And as SATA disks get faster and more reliable, secondary storage will continue to grow. There will always be a place for high-priced FC drives, but secondary storage is no longer a second-class citizen in the data center.
This was first published in August 2004