Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello,
I stumbled over this one, when the firmware of a storage controller
on a drbd secondaryy gets upgraded and freezes io for about 1 minute.
Because drbd is the storage base of a kvm cluster (via iscsi) the
load of all guests goes up very high and all writing prozesses in
the guest freezes (thats pretty ok - i think;-) until io again flows
on upgraded controller.
But what I've expected to happen is with ko-count set to 6 and timeout
is default of 6sec, that the primary will go to StandAlone mode after
36 seconds. But this does _not_ happen :-O
drbd.conf man page states:
ko-count number
In case the secondary node fails to complete a single write request
for count times the timeout, it is expelled from the cluster.
(I.e. the primary node goes into StandAlone mode.)
The default value is 0, which disables this feature.
I prepared a test case and reproduce the same behavor by suspend
io via dmsetup on a secondary with a lvm backed backing device.
So it looks like a bug?
(But maybe a missed something here ;-)
Kind Regards,
Roland
--
Roland.Friedwagner at wu.ac.at Phone: +43 1 31336 5377
IT Services - WU (Vienna University of Economics and Business)