Dear developers
I am testing the reliability of MDS in Ceph File System.
As we know, the default setting, there are one active MDS and one standby MDS.
I want to test the reliability of MDS.
Here is my testing scenario:
As easy to understand, here I assume the active MDS as mds0 and the
standby one is mds1.
I write data and stop the mds0 daemon by "ceph mds stop 0" at the same time.
Will the standby mds1 change its status to active?
I think the system should be normal and the data should not loss even
though there is just one MDS.
But there are many problem I met....><
(1) I want to know which mds is active and standby.
But there are different answer when I type different commands.
1. When I type "ceph mds stat".
It shows: (0=up: active), 1 up: standby
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Does it means mds0
is active and mds1 is standby ?
2.When I type "ceph mds dump -o -"
It shows: mds0 is standby and mds1 is active.
My question is: Why there are different status about mds0 and mds1?
Which one is correct?
(2) I want to know the issue about stoping the active mds.
If the command which "ceph mds stat" can show the active mds correctly,
the active mds must be mds0 and the other mds1 is standby.
So I type"ceph mds stop 0".
It shows: ‘telling mds0 192.168.200.185:6800/14819 to stop’(0)
^^^^^^^^^^^^^^^^^^ mds1's IP.
1. Why it shows the system stoping mds0 but mds1's IP ?
2. When I type "ceph -w", here is the log:
======================================
mds e43: 1/1/1 up {0=up:active}, 1 up standby
mds e44: 1/1/1 up {0=up:stoping}, 1 up standby
mds e45: 1/1/1 up {0=up:replay}
mds e46: 1/1/1 up {0=up:reconnect}
mds e47: 1/1/1 up {0=up:rejoin}
mds e44: 1/1/1 up {0=up:active}
=====================================
>From the log, which MDS does the system stop?
My command which is"ceph mds stop 0", but the log should not be {1=up:active}?
It really confuse me...
3. When I type"ceph mds dump –o –", here is the log:
4920: 192.168.200.184:6800/30000 ‘0’ mds0.12 up:active seq 40828
^^^^^^^^^^^^^^^^^^^ mds0's IP
Why does the system leave the mds0?
Please help me solving these problem, I am very confused...
Thanks a lot~~~^^
By the way, this is my testing environment :
==================================================================================
I set 7 servers which include 3 MONs(host1 host2 host3), 2 MDSs(host4
host5) and 2 OSDes(host6 host7).
The version ceph 0.26 is in my system.
==================================================================================
--
Best Regards,
Stefanie Chen
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