Re: Speeding Up "rbd ls -l <pool>" output

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> Op 9 februari 2017 om 9:13 schreef Özhan Rüzgar Karaman <oruzgarkaraman@xxxxxxxxx>:
> 
> 
> Hi;
> I am using Hammer 0.49.9 release on my Ceph Storage, today i noticed that
> listing an rbd pool takes to much time then the old days. If i have more
> rbd images on pool it takes much more time.
> 

It is the -l flag that you are using in addition. That flag opens each RBD image and stats the header of it to get the size.

A regular 'rbd ls' will only read the RADOS object rbd_directory, but it is the -l flag which causes the RBD tool to iterate over all the images and query their header.

> My clusters health is ok and currently there is no load on the cluster.
> Only rbd images are used to serve to vm's.
> 
> I am sending some information below. My level.db size is also 280 mb, i
> also compacted level.db to 40 mb size but again "rbd ls -l" output is too
> slow.
> 
> This timing is important for my vm deploy time to complete because when i
> refresh a pool/datastore it takes nearly to 20 seconds or more for 350 rbd
> images+snapshots.
> 
> Thanks for all help
> 
> Regards
> Ozhan Ruzgar
> 
> root@mont3:/var/lib/ceph/mon/ceph-mont3/store.db# ceph -s
>     cluster 6b1cb3f4-85e6-4b70-b057-ba7716f823cc
>      health HEALTH_OK
>      monmap e1: 3 mons at
> {mont1=172.16.x.x:6789/0,mont2=172.16.x.x:6789/0,mont3=172.16.x.x:6789/0}
>             election epoch 126, quorum 0,1,2 mont1,mont2,mont3
>      osdmap e20509: 40 osds: 40 up, 40 in
>       pgmap v20333442: 1536 pgs, 3 pools, 235 GB data, 63442 objects
>             700 GB used, 3297 GB / 3998 GB avail
>                 1536 active+clean
>   client io 0 B/s rd, 3785 kB/s wr, 314 op/s
> 
> root@mont1:~# time rbd ls -l cst2|wc -l
> 278
> 
> real 0m11.970s
> user 0m0.572s
> sys 0m0.316s
> root@mont1:~# time rbd ls -l cst3|wc -l
> 15
> 
> real 0m0.396s
> user 0m0.020s
> sys 0m0.032s
> root@mont1:~# time rbd ls -l cst4|wc -l
> 330
> 
> real 0m16.630s
> user 0m0.668s
> sys 0m0.336s
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