Improve RAID Speed with Partitions

During the last couple of months, I’ve been testing a lot of different storage from companies like Promise Technology, G-Technology and OWC, among others. Single drives, multiple drives and RAIDs.

I’ve known for a long time that hard drive speed varies as the drive fills up. Drives are at their fastest when they are empty. As they get closer and closer to full, they slow down. What I recently realized was that RAIDs behave the same way: empty RAIDs are really fast, while full RAIDs are much slower.

This is because hard drives, which are the essential storage component of a RAID, store data to the inner (faster) tracks first, then, as the drives fill up, data is stored to the outer tracks, which are slower.

THE “SECRET SAUCE”

We can take advantage of this fact to improve the overall speed of our RAIDs by partitioning them. (We can partition individual hard drives, too, but the performance benefits are much less significant. I no longer recommend partitioning single hard drives.)

What a partition does is divide the physical storage capacity of a RAID into separate logical “chunks.” Think of this as increasing the number of drawers in a filing cabinet. The overall cabinet does not increase in size, but by increasing the number of drawers it makes it easier to access files stored in the drawers. read more...