On 9/1/2011 12:48 PM, Daniel L. Miller wrote:
Given my extensive requirements - I haven't yet filled my existing 320GB
- size isn't a big deal. Am I actually deriving much benefit from 4-disk
RAID10 using 160GB discs - vs a 2-4 disc 1TB RAID1 array?
A pair of RAID-1 mirrors:
- easy to deal with
- you can attempt to manually balance load between the two arrays
(storage on one pair, indexes and mail queue on other pair)
- disks can be pulled and taken to another machine and read one by one
- slightly harder to screw up (but both setups die if the wrong 2 disks
fail)
RAID-10 over 4 disks:
- generally faster seeks
- generally faster read/write speeds due to striping
- generally the better choice for performance
- a bit harder to bury the disks vs a pair of mirrors
- lets you have a bigger partition
- all the eggs in a single array
If you're having performance problems on the existing RAID-10, your only
real choices are to throw more spindles at it (move to a 6 or 8 disk
RAID-10 w/ a hot-spare disk), throw faster spindles at it (10k/15k SAS),
or move to SSD.
So, if you think you can manually balance the needs of the system, you
could try a pair of independent mirrors. But if you want less hassle,
stick with the RAID-10.
(And look into a tool like "atop" which can be run in the terminal and
does a decent job of showing you whether the CPU/DISK is overly busy.)
