Guidelines for Stripes and Concatenations

• Concatenation uses less CPU cycles than striping and performs well for small random I/O and for even I/O distribution.

• When possible, distribute the components of a stripe or concatenation across different controllers and busses. Using stripes that are each on different controllers increases the number of simultaneous reads and writes that can be performed.

• If a stripe is defined on a failing controller and there is another available controller on the system, you can “move” the stripe to the new controller by moving the disks to the controller and redefining the stripe.

• Number of stripes: Another way of looking at striping is to first determine the performance requirements. For example, you might need 10.4 Mbyte/sec performance for a selected application, and each disk might deliver approximately 4 Mbyte/sec. Based on this formula, then determine how many disk spindles you need to stripe across:

  10.4 Mbyte/sec / 4 Mbyte/sec = 2.6

  Therefore, you need 3 disks capable of performing I/O in parallel.