28 Feb
2020
28 Feb
'20
11:07 a.m.
On Fri, Feb 28, 2020 at 9:35 AM <DHilsbos(a)performair.com> wrote:
Marc;
If I understand that command correctly, it's tells MDS 'c' to disappear, the
same as rebooting would, right?
Let me just clarify something then...
When I run ceph fs dump I get the following:
110248: [v2:10.2.80.10:6800/1470324937,v1:10.2.80.10:6801/1470324937] 'S700041'
mds.0.29 up:active seq 997315
120758: [v2:10.2.80.11:6800/2691008522,v1:10.2.80.11:6801/2691008522] 'S700042'
mds.0.0 up:standby-replay seq 2
Doesn't that indicate that the standby-replay server is out of date, and would need
to pause the FS to replay?
Is there something wrong in my setup, or is the above expected?
That seq value is not about how current it is on the FS state. But you
are right that even a standby-replay MDS will need to go through
*some* recovery.
This is usually fast, as standby-replay nodes should have just about
all the relevant metadata already cached, but they still need to
reconnect clients.
We aren't really set up for affirmatively migrating active state
between MDSes in the way you describe — if you have a multi-MDS config
you can "drain" one of the running daemons, but I think that's always
from the highest rank downwards, so you'd still need mds.0 to stay
alive. This is a good thought for dealing with extreme-HA
requirements, but I suspect you'll be okay with the standby-replay's
failover ability.
-Greg
Thank you,
Dominic L. Hilsbos, MBA
Director - Information Technology
Perform Air International Inc.
DHilsbos(a)PerformAir.com
www.PerformAir.com
-----Original Message-----
From: Marc Roos [mailto:M.Roos@f1-outsourcing.eu]
Sent: Friday, February 28, 2020 8:19 AM
To: ceph-users; Dominic Hilsbos
Subject: RE: [ceph-users] Stately MDS Transitions
ceph mds fail c?
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F1 Outsourcing Development Sp. z o.o.
Poland
t: +48 (0)124466845
f: +48 (0)124466843
e: marc(a)f1-outsourcing.eu
-----Original Message-----
From: DHilsbos(a)performair.com [mailto:DHilsbos@performair.com]
Sent: vrijdag 28 februari 2020 16:17
To: ceph-users(a)ceph.io
Subject: [ceph-users] Stately MDS Transitions
All;
We just started really fiddling with CephFS on our production cluster
(Nautilus - 14.2.5 / 14.2.6), and I have a question...
Is there a command / set of commands that transitions a standby-replay
MDS server to the active role, while swapping the active MDS to
standby-replay, or even just standby?
I'm looking for a way to seamlessly, and without down time, prepare the
active MDS to go offline (reboot) as part of planned /periodic
maintenance.
Thank you,
Dominic L. Hilsbos, MBA
Director - Information Technology
Perform Air International Inc.
DHilsbos(a)PerformAir.com
www.PerformAir.com
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