I am under the impression that mkfs.xfs is able to obtain details from
the Linux md subsystem, such that it will automatically create the
optimal sunit and swidth parameters, to suit an md RAID array on which
the filesystem is being created.
Please correct me if I am wrong.
If this is the case, then I am a little confused by the following:
mkfs.xfs -f -l logdev=/dev/md1,size=10000b /dev/md5
meta-data=/dev/md5 isize=256 agcount=32, agsize=7630656
= sectsz=4096 attr=0
data = bsize=4096 blocks=244179840, imaxpct=25
= sunit=64 swidth=128 blks, unwritten=1
naming =version 2 bsize=4096
log =/dev/md1 bsize=4096 blocks=10000, version=1
= sectsz=512 sunit=0 blks
realtime =none extsz=524288 blocks=0, rtextents=0
This is the output where /dev/md5 is a 3 disk RAID5, with a chunk size
After reading the man page and looking at some examples in the mailing
list archives, I would have thought that the best sizes would have been
sunit=32 and swidth=64, or am I wrong?
I ask, as I am about to resize this array by adding another drive and am
trying to work out the new values for these parameters, to pass to mount
- the values I have come up with are sunit=256 and swidth=768.