On Thu, Oct 20, 2016 at 10:15 PM, Kate Ward <kate.ward@xxxxxxxxxxxxx> wrote:
> I have a strange problem that began manifesting after I rebuilt my cluster a
> month or so back. A tiny subset of my files on CephFS are being zero-padded
> out to the length of ceph.dir.layout.stripe_unit when the files are later
> *read* (not when they are written). Tonight I realized the padding matched
> the stripe_unit value of 1048576, and changed it to 4194304, which resulted
> in those files that get padded taking on the new stripe_unit value. I've
> since changed it back. I've tried searching Google for answers, and Ceph
> bugs, but have had no luck so far.
>
> Current ceph.dir.layout setting for the entire cluster.
> $ getfattr -n ceph.dir.layout /ceph/ka
> getfattr: Removing leading '/' from absolute path names
> # file: ceph/ka
> ceph.dir.layout="stripe_unit=1048576 stripe_count=2 object_size=8388608
> pool=cephfs_data"
>
> Ceph is mounted on all machines using the kernel driver. The problem is not
> isolated to a single machine.
> $ grep /ceph/ka /etc/mtab
> backupz/ceph/ka /backupz/ceph/ka zfs rw,noatime,xattr,noacl 0 0
> 172.16.0.11:6789,172.16.0.19:6789:/ /ceph/ka ceph
> rw,noatime,nodiratime,name=admin,secret=<hidden>,acl 0 0
>
> Files from a Subversion repository, where the last one was padded after I
> tried to check out the repo.
> kward@ka02 2016-10-20T22:57:13
> %0]/ceph/ka/data/repoz/forestent/forestent/db/revs/0
> $ ls -lrt |tail -5
> -rw-r--r-- 1 www-data www-data 1079 Oct 20 08:53 877
> -rw-r--r-- 1 www-data www-data 1415 Oct 20 08:55 878
> -rw-r--r-- 1 www-data www-data 1059 Oct 20 09:01 879
> -rw-r--r-- 1 www-data www-data 1318 Oct 20 09:36 880
> -rw-r--r-- 1 www-data www-data 4194304 Oct 20 19:18 881
This issue isn't one I immediately recognise. What kernel version is
in use on the clients?
I would guess an issue like this comes from the file size recovery
that we do if/when a client loses contact while writing a file, which
I don't know that we ever test with non-default layouts, and might not
work very well with layouts that have stripe_unit != object_size.
If you set "debug mds = 10" and "debug filer = 10" on the MDS, and
then capture the log from the point in time where you write a file to
the point in time where the file is statted and gives the incorrect
size (if it's reproducible that readily), that should gives us a
better idea.
John
>
> Files stored, then later accessed via WebDAV. Only those files accessed were
> subsequently padded.
> [kward@ka02 2016-10-20T23:01:42 %0]~/www/webdav/OmniFocus.ofocus
> $ ls -l
> total 16389
> -rw-r--r-- 1 www-data www-data 4194304 Oct 20 20:08
> 00000000000000=ay-_KSusSw8+jOtYClSC2kx.zip
> -rw-r--r-- 1 www-data www-data 1383 Oct 20 19:22
> 20161020172209=pP4DpDOXAaA.client
> -rw-r--r-- 1 www-data www-data 4194304 Oct 20 20:20
> 20161020182047=pP4DpDOXAaA.client
> -rw-r--r-- 1 www-data www-data 4194304 Oct 20 21:11
> 20161020191117=pP4DpDOXAaA.client
> -rw-r--r-- 1 www-data www-data 1309 Oct 20 21:56
> 20161020195647=jY9iwiPfUhB.client
> -rw-r--r-- 1 www-data www-data 4194304 Oct 20 22:04
> 20161020200427=pP4DpDOXAaA.client
> -rw-r--r-- 1 www-data www-data 1309 Oct 20 22:54
> 20161020205415=jY9iwiPfUhB.client
>
> Cluster lists as healthy. (Yes, I'm aware one of the OSDs is currently down.
> The issue was there two months before it went down.)
> $ ceph status
> cluster f13b6373-0cdc-4372-85a2-66bf2841e313
> health HEALTH_OK
> monmap e3: 3 mons at
> {ka01=172.16.0.11:6789/0,ka03=172.16.0.15:6789/0,ka04=172.16.0.17:6789/0}
> election epoch 36, quorum 0,1,2 ka01,ka03,ka04
> fsmap e1140219: 1/1/1 up {0=ka01=up:active}, 2 up:standby
> osdmap e1234338: 16 osds: 15 up, 15 in
> flags sortbitwise
> pgmap v2296058: 1216 pgs, 3 pools, 7343 GB data, 1718 kobjects
> 14801 GB used, 19360 GB / 34161 GB avail
> 1216 active+clean
>
> Details:
> - Ceph 10.2.2 (Ubuntu 16.04.1 packages)
> - 4x servers, each with 4x OSDs on HDDs (mixture of 2T and 3T drives);
> journals on SSD
> - 3x Mons, and 3x MDSs
> - Data is replicated 2x
> - The only usage of the cluster is via CephFS
>
> Kate
> https://ch.linkedin.com/in/kate-ward-1119b9
>
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