1 Oct
2019
1 Oct
'19
3:09 a.m.
The thresholds were recently reduced by a factor of 10. I guess you
have a lot of (open) files? Maybe use more active MDS servers?
Or increase the thresholds, I wouldn't worry at all about 200k omap
keys if you are running on reasonable hardware.
The usual argument for a low number of omap keys is recovery time, but
if you are running a metadata-heavy workload on something that has
problems recovering 200k keys in less than a few seconds, then you are
doing something wrong anyways.
Paul
--
Paul Emmerich
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On Tue, Oct 1, 2019 at 9:10 AM Eugen Block <eblock(a)nde.ag> wrote:
>
> Hi all,
>
> we have a new issue in our Nautilus cluster.
> The large omap warning seems to be more common for RGW usage, but we
> currently only use CephFS and RBD. I found one thread [1] regarding
> metadata pool, but it doesn't really help in our case.
>
> The deep-scrub of PG 36.6 brought up this message (deep-scrub finished
> with "ok"):
>
> 2019-09-30 20:18:22.548401 osd.9 (osd.9) 275 : cluster [WRN] Large
> omap object found. Object: 36:654134d2:::mds0_openfiles.0:head Key
> count: 238621 Size (bytes): 9994510
>
>
> I checked xattr (none) and omapheader:
>
> ceph01:~ # rados -p cephfs-metadata listxattr mds0_openfiles.0
> ceph01:~ # rados -p cephfs-metadata getomapheader mds0_openfiles.0
> header (42 bytes) :
> 00000000 13 00 00 00 63 65 70 68 20 66 73 20 76 6f 6c 75 |....ceph fs volu|
> 00000010 6d 65 20 76 30 31 31 01 01 0d 00 00 00 74 c3 12 |me v011......t..|
> 00000020 00 00 00 00 00 01 00 00 00 00 |..........|
> 0000002a
>
> ceph01:~ # ceph fs volume ls
> [
> {
> "name": "cephfs"
> }
> ]
>
>
> The respective OSD has default thresholds regarding large_omap:
>
> ceph02:~ # ceph daemon osd.9 config show | grep large_omap
> "osd_deep_scrub_large_omap_object_key_threshold": "200000",
> "osd_deep_scrub_large_omap_object_value_sum_threshold":
"1073741824",
>
>
> Can anyone point me to a solution for this?
>
> Best regards,
> Eugen
>
>
> [1] http://lists.ceph.com/pipermail/ceph-users-ceph.com/2019-March/033813.html
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