[ClusterLabs] nfsserver_monitor() doesn't detect nfsd process is lost.

[yuta takeshita]

Hi,

Tanks for responding and making a patch.

2016-01-14 19:16 GMT+09:00 Dejan Muhamedagic <dejanmm at fastmail.fm>:

> On Thu, Jan 14, 2016 at 11:04:09AM +0100, Dejan Muhamedagic wrote:
> > Hi,
> >
> > On Thu, Jan 14, 2016 at 04:20:19PM +0900, yuta takeshita wrote:
> > > Hello.
> > >
> > > I have been a problem with nfsserver RA on RHEL 7.1 and systemd.
> > > When the nfsd process is lost with unexpectly failure,
> nfsserver_monitor()
> > > doesn't detect it and doesn't execute failover.
> > >
> > > I use the below RA.(but this problem may be caused with latest
> nfsserver RA
> > > as well)
> > >
> https://github.com/ClusterLabs/resource-agents/blob/v3.9.6/heartbeat/nfsserver
> > >
> > > The cause is following.
> > >
> > > 1. After execute "pkill -9 nfsd", "systemctl status nfs-server.service"
> > > returns 0.
> >
> > I think that it should be systemctl is-active. Already had a
> > problem with systemctl status, well, not being what one would
> > assume status would be. Can you please test that and then open
> > either a pull request or issue at
> > https://github.com/ClusterLabs/resource-agents
>
> I already made a pull request:
>
> https://github.com/ClusterLabs/resource-agents/pull/741
>
> Please test if you find time.
>
I tested the code, but still problems remain.
systemctl is-active retrun active and the return code is 0 as well as
systemctl status.
Perhaps it is inappropriate to use systemctl for monitoring the kernel
process.
Mr Kay Sievers who is a developer of systemd said that systemd doesn't
monitor kernel process in the following.
http://comments.gmane.org/gmane.comp.sysutils.systemd.devel/34367

I reply to your pull request.

Regards,
Yuta Takeshita

>
> Thanks for reporting!
>
> Dejan
>
> > Thanks,
> >
> > Dejan
> >
> > > 2. nfsserver_monitor() judge with the return value of "systemctl status
> > > nfs-server.service".
> > >
> > > ----------------------------------------------------------------------
> > > # ps ax | grep nfsd
> > > 25193 ?        S<     0:00 [nfsd4]
> > > 25194 ?        S<     0:00 [nfsd4_callbacks]
> > > 25197 ?        S      0:00 [nfsd]
> > > 25198 ?        S      0:00 [nfsd]
> > > 25199 ?        S      0:00 [nfsd]
> > > 25200 ?        S      0:00 [nfsd]
> > > 25201 ?        S      0:00 [nfsd]
> > > 25202 ?        S      0:00 [nfsd]
> > > 25203 ?        S      0:00 [nfsd]
> > > 25204 ?        S      0:00 [nfsd]
> > > 25238 pts/0    S+     0:00 grep --color=auto nfsd
> > > #
> > > # pkill -9 nfsd
> > > #
> > > # systemctl status nfs-server.service
> > > ● nfs-server.service - NFS server and services
> > >    Loaded: loaded (/etc/systemd/system/nfs-server.service; disabled;
> vendor
> > > preset: disabled)
> > >    Active: active (exited) since 木 2016-01-14 11:35:39 JST; 1min 3s ago
> > >   Process: 25184 ExecStart=/usr/sbin/rpc.nfsd $RPCNFSDARGS
> (code=exited,
> > > status=0/SUCCESS)
> > >   Process: 25182 ExecStartPre=/usr/sbin/exportfs -r (code=exited,
> > > status=0/SUCCESS)
> > >  Main PID: 25184 (code=exited, status=0/SUCCESS)
> > >    CGroup: /system.slice/nfs-server.service
> > > (snip)
> > > #
> > > # echo $?
> > > 0
> > > #
> > > # ps ax | grep nfsd
> > > 25256 pts/0    S+     0:00 grep --color=auto nfsd
> > > ----------------------------------------------------------------------
> > >
> > > It is because the nfsd process is kernel process, and systemd does not
> > > monitor the state of the kernel process of running.
> > >
> > > Is there something good way?
> > > (When I use "pidof" instead of "systemctl status", the faileover is
> > > successful.)
> > >
> > > Regards,
> > > Yuta Takeshita
> >
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