[root@sdw9 data1]# xfs_info /dev/sdd
meta-data="" isize=256 agcount=32, agsize=22469715 blks
= sectsz=512 attr=0
data = bsize=4096 blocks=719030880, imaxpct=25
= sunit=0 swidth=0 blks, unwritten=1
naming =version 2 bsize=4096
log =internal bsize=4096 blocks=32768, version=1
= sectsz=512 sunit=0 blks, lazy-count=0
realtime =none extsz=4096 blocks=0, rtextents=0
[root@sdw9 data1]# xfs_info /dev/sdb
meta-data="" isize=256 agcount=32, agsize=22469715 blks
= sectsz=512 attr=0
data = bsize=4096 blocks=719030880, imaxpct=25
= sunit=0 swidth=0 blks, unwritten=1
naming =version 2 bsize=4096
log =internal bsize=4096 blocks=32768, version=1
= sectsz=512 sunit=0 blks, lazy-count=0
realtime =none extsz=4096 blocks=0, rtextents=0
[root@sdw9 data1]# xfs_db -c frag -r /dev/sdb
actual 1799, ideal 1748, fragmentation factor 2.83%
[root@sdw9 data1]# xfs_db -c frag -r /dev/sdd
actual 54324, ideal 1749, fragmentation factor 96.78%
On 9/9/10 7:12 AM, "Eric Sandeen" <sandeen@xxxxxxxxxxx> wrote:
Brady Chang wrote:
> Hello All,
> I have an issue with fragmentation on a particular device
> thanks for any advice.
>
> -Brady
>
> I have a Dell r510 with 12 disks
> 2xraid 5 (6 disks each)
> raid group1:
> 48 GB carved out for os mounted as /
> remaining space 2.7 TB for xfs mounted as /data1
> raid group2:
> 48 GB for swap
> remaining space 2.7 TB for xfs mounted as /data2
>
> The strange thing is that /data1 never gets fragmented where as /data2
> is badly fragmented.
> I believe increase allocsize would help, but not sure how to explain why
> /data2(/dev/sdd) always gets fragmented and not /data1(/dev/sdb)
>
> It's a data warehouse application. the I/O is balanced between /data1
> and /data2:
> output of xfs_db
> [root@sdw4 data1]# xfs_db -c frag -r /dev/sdb
> actual 14353, ideal 13702, fragmentation factor 4.54%
> [root@sdw4 data1]# xfs_db -c frag -r /dev/sdd
> actual 408674, ideal 13719, fragmentation factor 96.64%
so each file has 30 extents on average (actual/ideal)
> df output
> /dev/sdb 2.7T 967G 1.8T 36% /data1
> /dev/sdd 2.7T 1.1T 1.7T 39% /data2
1.1T/408674 extents is ~3M per extent, not so good.
How many files are on each fs?
> LABEL=/data1 /data1 xfs
> allocsize=1048576,logbufs=8,noatime,nodiratime 0 0
> LABEL=/data2 /data2 xfs
> allocsize=1048576,logbufs=8,noatime,nodiratime 0 0
Everything but the first option is default, BTW.
Is xfs_info output on the 2 filesystems the same?
Otherwise Emmanuel's idea is a good one, maybe it's not
as balanced as you think it is, or maybe they have aged
differently and have different amounts of freespace
(see the freesp command in xfs_db)
> By the way, the os is RHEL 5.5 kernel 2.6.18-194.11.1.el5
Was Red Hat support not helpful?
-Eric
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