From: Keith Keller kkeller@wombat.san-francisco.ca.us
- 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/ht...
- 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