Hi Paul,

I tried ceph-fuse mounting it in a different mount point and it worked.

The problem here is we can't unmount ceph kernel client as it is in use

by some virsh processes. We forced the unmount and mount ceph-fuse

but we got an I/O error and mount -l cleared all the processes but after

rebooting the vm's they didn't come back and a server reboot was needed.

Not sure how can I restore mds session or remounting cephfs keeping

all processes.

Thanks a lot for your help.

Jaime


On 02/10/18 11:02, Paul Emmerich wrote:
Kernel 4.4 is not suitable for a multi MDS setup. In general, I
wouldn't feel comfortable running 4.4 with kernel cephfs in
production.
I think at least 4.15 (not sure, but definitely > 4.9) is recommended
for multi MDS setups.

If you can't reboot: maybe try cephfs-fuse instead which is usually
very awesome and usually fast enough.

Paul

Am Di., 2. Okt. 2018 um 10:45 Uhr schrieb Jaime Ibar <ja...@tchpc.tcd.ie>:
Hi Paul,

we're using 4.4 kernel. Not sure if more recent kernels are stable

for production services. In any case, as there are some production

services running on those servers, rebooting wouldn't be an option

if we can bring ceph clients back without rebooting.

Thanks

Jaime


On 01/10/18 21:10, Paul Emmerich wrote:
Which kernel version are you using for the kernel cephfs clients?
I've seen this problem with "older" kernels (where old is as recent as 4.9)

Paul
Am Mo., 1. Okt. 2018 um 18:35 Uhr schrieb Jaime Ibar <ja...@tchpc.tcd.ie>:
Hi all,

we're running a ceph 12.2.7 Luminous cluster, two weeks ago we enabled
multi mds and after few hours

these errors started showing up

2018-09-28 09:41:20.577350 mds.1 [WRN] slow request 64.421475 seconds
old, received at 2018-09-28 09:40:16.155841:
client_request(client.31059144:8544450 getattr Xs #0$
100002e1e73 2018-09-28 09:40:16.147368 caller_uid=0, caller_gid=124{})
currently failed to authpin local pins

2018-09-28 10:56:51.051100 mon.1 [WRN] Health check failed: 5 clients
failing to respond to cache pressure (MDS_CLIENT_RECALL)
2018-09-28 10:57:08.000361 mds.1 [WRN] 3 slow requests, 1 included
below; oldest blocked for > 4614.580689 secs
2018-09-28 10:57:08.000365 mds.1 [WRN] slow request 244.796854 seconds
old, received at 2018-09-28 10:53:03.203476:
client_request(client.31059144:9080057 lookup #0x100
000b7564/58 2018-09-28 10:53:03.197922 caller_uid=0, caller_gid=0{})
currently initiated
2018-09-28 11:00:00.000105 mon.1 [WRN] overall HEALTH_WARN 1 clients
failing to respond to capability release; 5 clients failing to respond
to cache pressure; 1 MDSs report slow requests,

Due to this, we decide to go back to single mds(as it worked before),
however, the clients pointing to mds.1 started hanging, however, the
ones pointing to mds.0 worked fine.

Then, we tried to enable multi mds again and the clients pointing mds.1
went back online, however the ones pointing to mds.0 stopped work.

Today, we tried to go back to single mds, however this error was
preventing ceph to disable second active mds(mds.1)

2018-10-01 14:33:48.358443 mds.1 [WRN] evicting unresponsive client
XXXXX: (30108925), after 68213.084174 seconds

After wait for 3 hours, we restarted mds.1 daemon (as it was stuck in
stopping state forever due to the above error), we waited for it to
become active again,

unmount the problematic clients, wait for the cluster to be healthy and
try to go back to single mds again.

Apparently this worked with some of the clients, we tried to enable
multi mds again to bring faulty clients back again, however no luck this
time

and some of them are hanging and can't access to ceph fs.

This is what we have in kern.log

Oct  1 15:29:32 05 kernel: [2342847.017426] ceph: mds1 reconnect start
Oct  1 15:29:32 05 kernel: [2342847.018677] ceph: mds1 reconnect success
Oct  1 15:29:49 05 kernel: [2342864.651398] ceph: mds1 recovery completed

Not sure what else can we try to bring hanging clients back without
rebooting as they're in production and rebooting is not an option.

Does anyone know how can we deal with this, please?

Thanks

Jaime

--

Jaime Ibar
High Performance & Research Computing, IS Services
Lloyd Building, Trinity College Dublin, Dublin 2, Ireland.
http://www.tchpc.tcd.ie/ | ja...@tchpc.tcd.ie
Tel: +353-1-896-3725

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--

Jaime Ibar
High Performance & Research Computing, IS Services
Lloyd Building, Trinity College Dublin, Dublin 2, Ireland.
http://www.tchpc.tcd.ie/ | ja...@tchpc.tcd.ie
Tel: +353-1-896-3725



--

Jaime Ibar
High Performance & Research Computing, IS Services
Lloyd Building, Trinity College Dublin, Dublin 2, Ireland.
http://www.tchpc.tcd.ie/ | ja...@tchpc.tcd.ie
Tel: +353-1-896-3725

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