[DRBD-user] Testing local-io-error handler -- blkid hangs and ties up drbd device

Lars Ellenberg lars.ellenberg at linbit.com
Thu Apr 12 15:24:25 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On Thu, Apr 12, 2012 at 09:14:38AM -0400, Chris Dickson wrote:
> Thanks for the quick reply,
> 
> My test handler currently isn't doing anything interesting, I just had it
> echo 'hello world' to a file which is located on a different drive than the
> LVM volume. The echo seems to have completed successfully as the file is
> written.
> 
> The end goal for the handler is to simply insert a row into a remote DB,
> other than that the default behavior on io-error of detaching is exactly
> what I would like to have happen.
> 
> I just tried filtering out drbd in lvm.conf and that doesn't seem to be the
> issue. After another try I did a quick ps auxf this showed up:
> 
> root       340  0.0  0.0  21392  1284 ?        Ss   12:59   0:00 udevd
> --daemon
> root       415  0.0  0.0  21384   896 ?        S    12:59   0:00  \_ udevd
> --daemon
> root      1775  0.0  0.0   8448   724 ?        D    13:04   0:00  |   \_
> /sbin/blkid -o udev -p /dev/drbd575
> 
> So it seems like udev is initiating the blkid call, could it be doing this
> before drbd has finished executing the handler?

If the handler finished,
(drbd prints "... helper command .... exit code ..." to the kernel log).
there is no reason for anything to hang.

DRBD is supposed to retry failed local requests on the peer, and if that
is not possible (no connection, or no good remote disk either), either
freeze IO (if so configured) or report IO errors back up the stack.

"Supposed to just work".

Maybe rather downgrade to 8.3.latest, I know we fixed some issues
in the retry logic on the way to 8.4.not-yet-but-"soon"-to-be-released.2

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com



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