On 6/9/2011 1:26 PM, John R Pierce wrote: > On 06/09/11 2:24 AM, Emmanuel Noobadmin wrote: >> Alternatively, if I mdraid mirror the existing disk, would md be smart >> enough to read using the other disk while the first's tied up with the >> first process? > > that woudl be my first choice, and yes, queued read IO could be > satisfied by either mirror, hence they'd have double the read performance. > > next step would be a raid 1+0 with yet more disks. > mdadm is good, but you'll never get double the read performance. Even on our 3-way mirrors (RAID 1, 3 active disks), we don't come close to twice the performance gain. RAID 1+0 with 4/6/8 spindles is the best way to ensure that you get better performance. Adding RAM to the server so that you have a larger read buffer might also be an option.