From: Keith Keller <kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx>
> 1) The controller node has two 90GB SSDs that I plan to use as a
> bootable RAID1 system disk. What is the preferred method for laying
> out the RAID array?
See the "Deployment Considerations" about SSDs and RAID:
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/newmds-ssdtuning.html
> 2) With large arrays you often hear about "aligning the filesystem to
> the disk". Is there a fairly standard way (I hope using only CentOS
> tools) of going about this? Are the various mkfs tools smart enough to
> figure out how an array is aligned on its own, or is sysadmin
> intervention required on such large arrays? (If it helps any, the disk
> array is backed by a 3ware 9750 controller. I have not yet decided how
> many disks I will use in the array, if that influences the alignment.)
>From memory:
For alignment, first partition starts at 2048.
For filesystem, call mkfs with appropriate -E stride=xxx,stripe-width=yyy
Stride = RAID Stripeisize_KB / FS blocksize_KB
Stripe-width = Stride * RAID_number_of_data_holding_disks (RAID6 = n-2 by example)
JD
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