Re: swidth with mdadm and RAID6

Shailendra Tripathi
2006-09-18T14:51:16Z

Can you list the output of
1. cat /proc/mdstat
2. the command to create 8+2 RAID6 with one spare ?
3. and output of following:
xfs_db -r /dev/md*
xfs_db> sb
xfs_db> p

-shailendra

Steve Cousins wrote:
> I have a RAID6 array of 11 500 GB drives using mdadm. There is one
> hot-spare so the number of data drives is 8. I used mkfs.xfs with
> defaults to create the file system and it seemed to pick up the chunk size
> I used correctly (64K) but I think it got the swidth wrong. Here is what
> xfs_info says:
>
> ===========================================================================
> meta-data=/dev/md0 isize=256 agcount=32, agsize=30524160
> blks
> = sectsz=4096 attr=0
> data = bsize=4096 blocks=976772992, imaxpct=25
> = sunit=16 swidth=144 blks, unwritten=1
> naming =version 2 bsize=4096
> log =internal bsize=4096 blocks=32768, version=2
> = sectsz=4096 sunit=1 blks
> realtime =none extsz=589824 blocks=0, rtextents=0
> ===========================================================================
>
> So, sunit*bsize=64K, but swidth=144 and swidth/sunit=9 so it looks like it
> thought there were 9 data drives instead of 8.
>
> Am I diagnosing this correctly? Should I recreate the array and
> explicitly set sunit=16 and swidth=128?
>
> Thanks for your help.
>
> Steve
> ______________________________________________________________________
> Steve Cousins, Ocean Modeling Group Email: cousins@umit.maine.edu
> Marine Sciences, 452 Aubert Hall http://rocky.umeoce.maine.edu
> Univ. of Maine, Orono, ME 04469 Phone: (207) 581-4302
>
>