Hi Philipp,

This looks like https://tracker.ceph.com/issues/61950, which was
closed as not reproducible.

Do you have any more background context about that cluster that might
give a clue how this happened? maybe a recent daemon
upgrade/restart/...?

Cheers, Dan

On Mon, Nov 17, 2025 at 8:28 AM Philipp Hocke <[email protected]> wrote:
>
> Hi,
>
> last week we had a "large omap" warning in one of our clusters. The
> affected object was
>
> 025-11-09T23:31:24.799+0000 7f70131b3640  0 log_channel(cluster) log
> [WRN] : Large omap object found. Object:
> 2:ddb71591:::mds1_openfiles.d:head PG: 2.89a8edbb (2.b) Key count:
> 200001 Size (bytes): 12122520
>
> I wanted to get a deeper understanding on what triggers this specific issue
> and had a look at the code - I'm not that deep into C++, so please, correct
> me if I'm wrong.
>
> If I understand correctly, LARGE_OMAP warnings are only generated (and
> cleared) during deep-scrubs. If an object is found with more keys
> than osd_deep_scrub_large_omap_object_key_threshold, it will trigger the
> warning. In this case
>
> mds1_openfiles.d had a Key count of 200001 while this specific option
> got deep-scrubbed and that triggered the warning
>
> The MDS should create a new openfiles fragment when the threshold is reached.
>
> My question is: How exactly does the MDS end up with an openfiles
> segment with more than 200000? Shouldn't the MDS create a new segment
> as soon as the previous one reaches the configured limit?
>
> If this is considered a bug, I'm happy to open a report.
>
>
> Best regards
>
> Philipp
>
> --
>
> Philipp Hocke
> Leiter Linux Systemadministration / Head Of TechOps
> CM4ALL GmbH
> Im Mediapark 6A - 50670 Köln / Cologne
> Phone +49-(0)221-6601-0 <https://outlook.office.com/mail/sentitems>
> Fax +49-(0)221-6601-1011 <https://outlook.office.com/mail/sentitems>
> E-Mail: [email protected]
> Internet: www.cm4all.com
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-- 
Dan van der Ster
Ceph Executive Council | CTO @ CLYSO
Try our Ceph Analyzer -- https://analyzer.clyso.com/
https://clyso.com | [email protected]
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