I need to set up an XFS filesystem on top of LVM on top of a hardware RAID-6 (10x 6TB + 2 parity) and I found the guideline on http://xfs.org/index.php/XFS_FAQ ("How to calculate the correct sunit,swidth values for optimal performance") which recommends:

When creating XFS filesystem on top of LVM on top of hardware raid please use sunit/swith values as when creating XFS filesystem directly on top of hardware raid.

I understand that the value for sunit is the stripe size defined during RAID volume creation and swidth is the number of data disks (e.g. 10 in the example above).

If I want to create e.g. 2 logical volumes with 12 TB and 30 TB, would I still use swidth=10 for both XFS filesystems or would I use swidth=2 and swidth=5 consistent with the 2 and 5 data disks which (mathematically) make up those logical volumes?

  1. You must use swidth=10, for all partitions
  2. Modern linux systems can calculate and use sunit/swith sizes automatically. There is no need to calculate it manualy, in most cases.

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