Re: millions of hex 80 0_0000 omap keys in single index shard for single bucket

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these keys starting with "<80>0_" appear to be replication log entries
for multisite. can you confirm that this is a multisite setup? is the
'bucket sync status' mostly caught up on each zone? in a healthy
multisite configuration, these log entries would eventually get
trimmed automatically

On Wed, Sep 20, 2023 at 7:08 PM Christopher Durham <caduceus42@xxxxxxx> wrote:
>
> I am using ceph 17.2.6 on Rocky 8.
> I have a system that started giving me large omap object warnings.
>
> I tracked this down to a specific index shard for a single s3 bucket.
>
> rados -p <indexpool> listomapkeys .dir.<zoneid>.bucketid.nn.shardid
> shows over 3 million keys for that shard. There are only about 2
> million objects in the entire bucket according to a listing of the bucket
> and radosgw-admin bucket stats --bucket bucketname. No other shard
> has anywhere near this many index objects. Perhaps it should be noted that this
> shard is the highest numbered shard for this bucket. For a bucket with
> 16 shards, this is shard 15.
>
> If I look at the list of omapkeys generated, there are *many*
> beginning with "<80>0_0000", almost the entire set of the three + million
> keys in the shard. These are index objects in the so-called 'ugly' namespace. The rest ofthey omapkeys appear to be normal.
>
> The 0_0000 after the <80> indicates some sort of 'bucket log index' according to src/cls/rgw/cls_rgw.cc.
> However, using some sed magic previously discussed here, I ran:
>
> rados -p <indexpool> getomapval .dir.<zoneid>.bucketid.nn.shardid --omap-key-file /tmp/key.txt
>
> Where /tmp/key.txt contains only the funny <80>0_0000 key name without a newline
>
> The output of this shows, in a hex dump, the object name to which the index
> refers, which was at one time a valid object.
>
> However, that object no longer exists in the bucket, and based on expiration policy, was
> previously deleted. Let's say, in the hex dump, that the object was:
>
> foo/bar/baz/object1.bin
>
> The prefix foo/bar/baz/ used to have 32 objects, say foo/bar/baz/{object1.bin, object2.bin, ... }
> An s3api listing shows that those objects no longer exist (and that is OK, as they  were previously deleted).
> BUT, now, there is a weirdo object left in the bucket:
>
> foo/bar/baz/ <- with the slash at the end, and it is an object not a PRE (fix).
>
> All objects under foo/ have a 3 day lifecycle expiration. If I wait(at most) 3 days, the weirdo object with '/'
> at the end will be deleted, or I can delete it manually using aws s3api. But either way, the log index
> objects, <80>0_0000.... remain.
>
> The bucket in question is heavily used. But with over 3 million of these <80>0_0000 objects (and growing)
> in a single shard, I am currently at a loss as to what to do or how to stop this from occuring.
> I've poked around at a few other buckets, and I found a few others that have this problem, but not enoughto cause a large omap warning. (A few hundred <80>0_000.... index objects in a shard), no where near enoughto cause the large omap warning that led me to this post.
>
> Any ideas?
>
>
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