swalloc/allocsize question

swalloc/allocsize question

[Joe Landman]

Hi folks:

   I've noticed some "odd" behavior while experimenting with xfs mounts 
on relatively recent kernels (3.18 series).  Basically, the 
swalloc,allocsize=x options are being modified to something different.  
That is:

root@usn-04:~/burn-in/fio# uname -r
3.18.12.scalable

root@usn-04:~/burn-in/fio# mount -o 
inode64,noatime,nodiratime,swalloc,allocsize=1280k /dev/sda /data/1

root@usn-04:~/burn-in/fio# mount | grep sda
/dev/sda on /data/1 type xfs 
(rw,noatime,nodiratime,swalloc,attr2,inode64,allocsize=256k,noquota)

This is a hardware RAID6 with a 128k chunk size and 12 elements (so 10 
data drives, thus the 1280k allocsize for stripe width allocation).  Is 
this something specific to xfs itself, or is this an issue in the mount 
tools ?

FWIW: we are using xfs-tools 3.2.2, kernel 3.18.12.  I've also seen this 
with the 3.10 series though, so I am not sure where to look to track 
this down.  Any guidance/suggestion?  Thanks!

Joe

joe.landman@gmail.com


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Re: swalloc/allocsize question

[Dave Chinner]

On Mon, Aug 03, 2015 at 01:27:03PM -0400, Joe Landman wrote:
> Hi folks:
> 
>   I've noticed some "odd" behavior while experimenting with xfs
> mounts on relatively recent kernels (3.18 series).  Basically, the
> swalloc,allocsize=x options are being modified to something
> different.  That is:
> 
> root@usn-04:~/burn-in/fio# uname -r
> 3.18.12.scalable
> 
> root@usn-04:~/burn-in/fio# mount -o
> inode64,noatime,nodiratime,swalloc,allocsize=1280k /dev/sda /data/1
> 
> root@usn-04:~/burn-in/fio# mount | grep sda
> /dev/sda on /data/1 type xfs
> (rw,noatime,nodiratime,swalloc,attr2,inode64,allocsize=256k,noquota)
> 
> This is a hardware RAID6 with a 128k chunk size and 12 elements (so
> 10 data drives, thus the 1280k allocsize for stripe width
> allocation).  Is this something specific to xfs itself, or is this
> an issue in the mount tools ?

Please provide:

	- xfs_info output from the filesystem in question
	- dmesg output of all the mount messages

Dave.
-- 
Dave Chinner
david@fromorbit.com

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