Dell PowerEdge RAID Controller 11 User’s Guide PERC H755, H750, H355, and H350 Controller Series

When configuring the virtual disks, you should consider the workload intended; RAID 1: for simple boot disk; RAID 5 or 6: for file or web servers (sequential reads/writes of files); RAID 10: for transactional database (small random reads and writes).

Virtual disks configured on hard drives should use the controller default cache setting of Write Back and Read Ahead.

Virtual disks configured on SSDs can use the same controller defaults settings as hard drives. Most users perform a copy of OS files or a data base to the new array. This setting provides optimum performance in this configuration.

Once the copy is complete, the array can be used as it is depending on the number and type of SSDs. It is recommended to enable FastPath by changing the controller's Write cache policy to Write Through and the Read cache policy to No Read Ahead. FastPath is developed to achieve the best random read/write performance from SSDs.

Only IO block sizes smaller than the virtual disk's stripe size are eligible for FastPath. In addition, there should be no background operations (rebuild, initialization) running on the virtual disks. FastPath is disabled if there is active background operation.