hi Yan
1. run "ceph mds fail" before rebooting host
2. host reboot by itself for some reason
you means no data get lost in the BOTH conditions?
in my test, i echo the date string per second into the file under cephfs dir,
when i reboot the master mds, there are 15 lines got lost.
thanks
13605702596@xxxxxxx
From: Yan, ZhengDate: 2017-12-18 09:55CC: John Spray; ceph-usersSubject: Re: cephfs miss data for 15s when master mds rebootingOn Mon, Dec 18, 2017 at 9:24 AM, 13605702596@xxxxxxx<13605702596@xxxxxxx> wrote:> 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?>no data get lost in this condition. just IO stall for a few seconds> thanks>> ________________________________> 13605702596@xxxxxxx>>> From: John Spray> Date: 2017-12-15 18:08> To: 13605702596@xxxxxxx> CC: ceph-users> Subject: Re: cephfs miss data for 15s when master mds rebooting> On Fri, Dec 15, 2017 at 1:45 AM, 13605702596@xxxxxxx> <13605702596@xxxxxxx> 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>>>> ________________________________>> 13605702596@xxxxxxx>>>> _______________________________________________>> ceph-users mailing list>> ceph-users@xxxxxxxxxxxxxx>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com>>>>> _______________________________________________> ceph-users mailing list> ceph-users@xxxxxxxxxxxxxx> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com>
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