Thanks. I'll take a look at the netlink interface. Not using multipath
for now, but will do so later.

For basic monitoring of storage network problems, here's what I am
thinking:
1. If there is a network failure, eventually cat /sys/block/<disk>/
device/state should show "offline" ?
2. How long will this take? I know that this is a function of
replacement_timeout, noop_interval, noop_timeout and scsi timeout, but
the relationship is not clear

Let us say
a=session.timeo.noop_out_interval=5
b=session.timeo.noop_out_timeout=5
c=session.timeo.replacement_timeout=120
d=`cat /sys/block/<disk>/device/timeout`=60

The disk should go offline in a maximum of a+b+c+d=190s after a
network failure?

If the network comes back up, how soon will the disk state go to
'running' ?

Thanks
--
solidguy


On Sep 10, 12:08 pm, Mike Christie <micha...@cs.wisc.edu> wrote:
> On 09/10/2009 12:53 PM, solidguy wrote:
>
> > Is there a good way to monitor the iscsi sessions for errors? I need
> > to report it via SNMP (and perhaps kill the VM running over the
> > connection). Right now the only way I see is to monitor syslog -- but
> > the syslog doesn't always give me which session (or disk) is in
> > trouble.
>
> You can monitor which sessions have errors by listening on the iscsi
> netlink interface. I am not sure if that is very user friendly. You
> would have to listen for ISCSI_KEVENT_CONN_ERROR events and filter out
> other junk. This does not tell you if a disk has errors though.
>
> For upstream we are working on a more complete solution for
> dm-mutlipath, so it can figure out when session/connections have link
> problems or if a disk is offlined by the scsi eh. But right now, I do
> not think there is any easy way to do what you need.
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