[pve-devel] iscsi, some hang : pvestatd always do iscsi_session_rescan

[Dietmar Maurer]

You want me to implement that? Or will you send a patch?

> -----Original Message-----
> From: Alexandre DERUMIER [mailto:aderumier at odiso.com]
> Sent: Freitag, 27. April 2012 10:39
> To: Dietmar Maurer
> Cc: pve-devel at pve.proxmox.com
> Subject: Re: [pve-devel] iscsi, some hang : pvestatd always do
> iscsi_session_rescan
> 
> 
> >> Well, I think the problem is that you iscsi server is slow.
> Yes indeed, the san was overload yesterday.
> Also I have 2 scsi controllers (active/passive), failover can take 2min. (vm can
> handle this)
> 
> 
> But the problem it's that proxmox become unresponsive when calling the
> iscsiadm during this time also pvestatd hang, so rrds for vm stats are not
> updated during this time.
> And with ha cluster, maybe fencing can be call ? (don't have tested it)
> 
> 
> >>Forcing a timeout is easy (we have a timeout parameter for
> run_command()).
> 
> oh great!
> 
> >>The question is what timeout do you want?
> 
> I think 5sec timeout must be enough for session rescan.
> 
> root at kvm6:~# time /usr/bin/iscsiadm --mode session -r 1 -R
> 
> real    0m0.616s
> user    0m0.003s
> sys     0m0.084s
> root at kvm6:~# time /usr/bin/iscsiadm --mode session -r 1 -R Rescanning
> session [sid: 1, target: iqn.1986-03.com.sun:02:316dd6a9-76bc-62ea-93fa-
> d0140e876a4b, portal: 10.6.0.18,3260]
> 
> real    0m0.764s
> user    0m0.006s
> sys     0m0.114s
> root at kvm6:~# time /usr/bin/iscsiadm --mode session -r 1 -R Rescanning
> session [sid: 1, target: iqn.1986-03.com.sun:02:316dd6a9-76bc-62ea-93fa-
> d0140e876a4b, portal: 10.6.0.18,3260]
> 
> real    0m0.753s
> user    0m0.005s
> sys     0m0.077s
> root at kvm6:~# time /usr/bin/iscsiadm --mode session -r 1 -R Rescanning
> session [sid: 1, target: iqn.1986-03.com.sun:02:316dd6a9-76bc-62ea-93fa-
> d0140e876a4b, portal: 10.6.0.18,3260]
> 
> real    0m0.734s
> user    0m0.005s
> sys     0m0.094s
> 
> 
> Thanks !
> Alexandre
> 
> 
> 
> ----- Mail original -----
> 
> De: "Dietmar Maurer" <dietmar at proxmox.com>
> À: "Alexandre DERUMIER" <aderumier at odiso.com>, pve-
> devel at pve.proxmox.com
> Envoyé: Vendredi 27 Avril 2012 10:12:46
> Objet: RE: [pve-devel] iscsi, some hang : pvestatd always do
> iscsi_session_rescan
> 
> > I check more deeply,
> > the main problem seem to be that iscsiadm have a long timeout.
> 
> Well, I think the problem is that you iscsi server is slow.
> 
> > (In fact the iscsi timeout, so it can be huge in some config with
> > iscsi failover, or if a path fail).
> >
> > Maybe can we implemented some kind of "kill process iscsiadm" if it
> > take too much time ?
> >
> >
> > I see that "timelimit" package exist in debian, "timelimit
> > /usr/bin/iscsiadm/ ...."
> >
> > maybe this can add some protections to iscsiadm command?
> 
> Forcing a timeout is easy (we have a timeout parameter for
> run_command()).
> 
> The question is what timeout do you want?
> 
> - Dietmar
> 
> 
> 
> --
> 
> --
> 
> 
> 
> 
> 	Alexandre D erumier
> Ingénieur Système
> Fixe : 03 20 68 88 90
> Fax : 03 20 68 90 81
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