I'm new here, and also new to RAID.
I just bought a LSI RAID card and 3 new 2TB HDDs (together with 2 old
ones), and trying to build a RAID5 volume.
Because I don't have spare drives, I'm doing like this: use the 3 new
ones to build RAID5, then create a LVM VG on it as partition table, make
an XFS (as well as a BTRFS for profile and personal data) on it. Then
grow it to 5 drives use MegaCLi, do a vgextend, then xfs_growfs.
Now the question is, I cannot deside sw of XFS
(https://raid.wiki.kernel.org/index.php/RAID_setup#XFS). I think I
should use 4(5-1), but it has poor performance (~140MB/s while raw disk
write is ~250M). Is this all right? Or should I specify sunit and swidth
in the mount options? I don't really know the mechanic of XFS on this,
does this have effect on read?
Additionally, I want to know if this is the optimal method for me or
just use GPT? Maybe I will grow the array to more disks later.
Any help is appreciated.