I am replying to this because I found the answer. I hope this little
bit of information helps others confused by the xfs documentation.
while sunit and swidth have to be set with the block size value in 512
bytes (sunit) and as a multiple of that 512 bytes (swidth), The values
returned by mkfs.xfs and xfs_info are listed as multiples of the block
size. In most cases I believe this will be 4096 but is subject to
change based on options. So the values I set were indeed being used but
just displayed poorly. For my sunit value of 512 the (64*4096) is
correct and my swidth value of 2560 (320*4096) is correct also. Hope
this helps someone else....
Robert
Robert Goley wrote:
I have not used xfs in a couple years but want to for a new server. I
have followed all the xfs documentation I could find. I believe my
commands are correct but am not seeing the results I expected from the
documentation. The issues occur with the sunit and swidth values. I
have a hardware raid5 array with 6 disks and a 256k strip size. I
have created a LVM volume using the -I option with 256k for the
value. I am creating the xfs filesystem with the following command:
"mkfs.xfs -f -b size=4096 -l size=128m -d
sunit=512,swidth=2560,agsize=3g -L test /dev/raidvg/test"
It displays this info...
meta-data=/dev/raidvg/test isize=256 agcount=34,
agsize=786432 blks
= sectsz=512 attr=2
data = bsize=4096 blocks=26214400, imaxpct=25
= sunit=64 swidth=320 blks
naming =version 2 bsize=4096 log =internal
log bsize=4096 blocks=32768, version=2
= sectsz=512 sunit=64 blks, lazy-count=0
realtime =none extsz=4096 blocks=0, rtextents=0
I tried mounting with with the command recommended below as well as
without options.
mount -o sunit=512,swidth=2560,noatime,nodiratime,logbufs=8
/dev/raidvg/test /test
Here are the results from xfs_info:
meta-data=/dev/mapper/raidvg-test isize=256 agcount=34,
agsize=786432 blks
= sectsz=512 attr=2
data = bsize=4096 blocks=26214400, imaxpct=25
= sunit=64 swidth=320 blks
naming =version 2 bsize=4096 log
=internal bsize=4096 blocks=32768, version=2
= sectsz=512 sunit=64 blks, lazy-count=0
realtime =none extsz=4096 blocks=0, rtextents=0
As you can see, these values do not match the settings I told it to
use. If I use sunit=4096 and swidth=20480 values instead, It
correctly shows the values I wanted in mkfs.xfs and xfs_info as long
as I do not specify different values in the mount options. Using
"mount /dev/raidvg/test /test" or "mount -o
sunit=4096,swidth=20480,noatime,nodiratime,logbufs=8 /dev/raidvg/test
/test" it will show the values I expected to see for my setup. Here
is an xfs_info of those mounts.
meta-data=/dev/mapper/raidvg-test isize=256 agcount=34,
agsize=786432 blks
= sectsz=512 attr=2
data = bsize=4096 blocks=26214400, imaxpct=25
= sunit=512 swidth=2560 blks
naming =version 2 bsize=4096 log
=internal bsize=4096 blocks=32768, version=2
= sectsz=512 sunit=64 blks, lazy-count=0
realtime =none extsz=4096 blocks=0, rtextents=0
Can anyone explain these results? It does not match up with anything
I have found on the web. Is this a bug?
Robert
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