hi John
thanks for your answer.
in normal condition, i can run "ceph mds fiail" before reboot.
but if the host reboots by itself for some reason, i can do nothing!
if this happens, data must be losed.
so, is there any other way to stop data from being losed?
thanks
13605702...@163.com
From: John Spray
Date: 2017-12-15 18:08
To: 13605702...@163.com
CC: ceph-users
Subject: Re: [ceph-users] cephfs miss data for 15s when master mds rebooting
On Fri, Dec 15, 2017 at 1:45 AM, 13605702...@163.com
<13605702...@163.com> wrote:
> hi
>
> i used 3 nodes to deploy mds (each node also has mon on it)
>
> my config:
> [mds.ceph-node-10-101-4-17]
> mds_standby_replay = true
> mds_standby_for_rank = 0
>
> [mds.ceph-node-10-101-4-21]
> mds_standby_replay = true
> mds_standby_for_rank = 0
>
> [mds.ceph-node-10-101-4-22]
> mds_standby_replay = true
> mds_standby_for_rank = 0
>
> the mds stat:
> e29: 1/1/1 up {0=ceph-node-10-101-4-22=up:active}, 1 up:standby-replay, 1
> up:standby
>
> i mount the cephfs on the ceph client, and run the test script to write data
> into file under the cephfs dir,
> when i reboot the master mds, and i found the data is not written into the
> file.
> after 15 seconds, data can be written into the file again
>
> so my question is:
> is this normal when reboot the master mds?
> when will the up:standby-replay mds take over the the cephfs?
The standby takes over after the active daemon has not reported to the
monitors for `mds_beacon_grace` seconds, which as you have noticed is
15s by default.
If you know you are rebooting something, you can pre-empt the timeout
mechanism by using "ceph mds fail" on the active daemon, to cause
another to take over right away.
John
> thanks
>
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