I have the following hardware:
1x - Areca ARC-1680IX-24 PCIe x8 SAS RAID Card 24x - Seagate Barracuda LP 2 TB 5900RPM SATA 3 GB/s 32 MB Cache 3.5-Inch Internal Hard Drive ST32000542AS
I plan on setting up the following volumes on the RAID controller.
Volume Info for RAIDSET #1, 4x 2tb drives: V#1 RAID10,10gb - 4k stripe size V#2 RAID10,3tb - 4k stripe size V#3 RAID0,2tb - 128k stripe size Volume Info for RAIDSET #2, 6x 2tb drives: V#4 RAID0,300gb - 4k stripe size V#5 RAID5,7.8tb - 64k stripe size Volume Info for RAIDSET #3, 6x 2tb drives: Volume Info for RAIDSET #4, 6x 2tb drives: V#6 RAID50,20tb or RAID60,16tb - 128k stripe size
I have concerns with alignment and stripe size when I setup these volumes in the RAID controller. I know with a regular HDD it is important to get the partition properly aligned for good performance, I am assuming I need to worry about this also when setting up the RAID volumes? Or will the RAID controller make sure the alignment is optimal?
My next concern is how this alignment affects the LVM volumes. Does the RAID controller notify the LVM driver how to properly align within the RAID volume?
I have a choice of many stripe sizes, from 4k all the way up to 128k. Will the selection of the stripe size affect my alignment and/or allocation sizes of the RAID volumes, e.g. if I choose 128k strip sizes on a RAID set with 4 disks that will be setup in RAID 0, should I make my RAID volume size a multiple of 512k? Also, what is an optimal stripe size for a linux root and swap partition or just general use?
Lastly, the RAID controller exposes a 3 channel SCSI controller, is there any performance benefit of splitting up my load across the 3 channels or is that just so it can support more disks?