[DRBD-user] Syncer's "after" dependency for online verifying

Lars Ellenberg lars.ellenberg at linbit.com
Fri Jun 1 17:50:23 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 Fri, Jun 01, 2012 at 12:03:20PM +0200, Lionel Sausin wrote:
> Dear DRBD community,
> We're using DRBD 8.3.11 with 2 resources called A and B.
> B is configured to sync after A, but when I run "drbdadm verify all"
> both resources start verifying immediately.

That is intentional.

In error scenarios, you do not have much control over when a network
fails/recovers, or a node reboots.
So there we have dependencies to not overload the system
with too much parallel resync activity.

For verify, that is entirely triggered from userspace,
you have full controll.

> Is it possible to have DRBD verify B only when A is done verifying?

Just don't start the verify on B while the verify on A is still running.


 for minor in 0 1 2 ; do
 	drbdsetup $minor verify ; drbdsetup $minor wait-sync

Or similar.

> If not, has it been/will it be possible in versions after 8.3.11?

I don't see any kernel support for "verify dependencies" coming soon,
as you can easily serialize verify operations in userland.

now that we have the dynamically adaptive resync rate controller,
and it is used for verify as well, for most cases I'd recommend
to enable it globally, and get rid of the resync dependencies.

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

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