On Tue, Mar 7, 2017 at 9:17 AM, Xiaoxi Chen <superdebuger at gmail.com> wrote:
> Hi,
>
> From the admin socket of mds, I got following data on our
> production cephfs env, roughly we have 585K inodes and almost same
> amount of caps, but we have>2x dentries than inodes.
>
> I am pretty sure we dont use hard link intensively (if any).
> And the #ino match with "rados ls --pool $my_data_pool}.
>
> Thanks for any explanations, appreciate it.
>
>
> "mds_mem": {
> "ino": 584974,
> "ino+": 1290944,
> "ino-": 705970,
> "dir": 25750,
> "dir+": 25750,
> "dir-": 0,
> "dn": 1291393,
> "dn+": 1997517,
> "dn-": 706124,
> "cap": 584560,
> "cap+": 2657008,
> "cap-": 2072448,
> "rss": 24599976,
> "heap": 166284,
> "malloc": 18446744073708721289,
> "buf": 0
> },
>
One possibility is that you have many "null" dentries, which are
created when we do a lookup and a file is not found -- we create a
special dentry to remember that that filename does not exist, so that
we can return ENOENT quickly next time. On pre-Kraken versions, null
dentries can also be left behind after file deletions when the
deletion is replayed on a standbyreplay MDS
(http://tracker.ceph.com/issues/16919)
John
>
> Xiaoxi
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