[ClusterLabs] Detect when corosync has started
ccaulfie at redhat.com
Tue Sep 1 04:33:25 EDT 2015
On 28/08/15 16:37, Brian Campbell wrote:
> I'm running Corosync/Pacemaker on an Ubuntu derivative, and to make
> them easier to manage wrote upstart jobs to start them up rather than
> using the init scripts.
> After doing so, my config scripts, which start up corosync and
> pacemaker and then configure them appropriately, start failing, I'm
> assuming because the upstart job returns slightly more quickly than
> the init scripts did. If I add a short sleep before configuring them,
> it succeeds.
> However, that short sleep would make every configuration operation a
> little bit more slow, so I don't want to do that every time I
> reconfigure. I would like instead to check if corosync is functional,
> and then poll it a few times until it finishes starting if it's not
> running, rather than just unconditionally sleeping for an arbitrary
> amount of time.
> Is checking the return value from "corosync-cfgtool -s" the best way
> to determine this? On systems with corosync running, it returns 0,
> while on those where it's not running, it returns 1. Is that a
> reliable way to tell if it's up and responding?
That will tell you if corosync is running. What it won't tell you is if
there are any other nodes in the cluster yet - so it could still be in
the joining phase. But it's probably the best option there is at the
moment. Depending on what you actually need, using corosync-quorumtool
to determine whether the cluster has quorum might be more useful.
cman_tool in RHEL5/6 had an option to wait until the cluster was up and
(optionally) had quorum. I wonder if this might be useful for corosync?
> Likewise, what's the best way to tell if Pacemaker is up, and able to
> be configured? Just check the status of "crm_mon -X"? That does seem
> to return success when it's running, and failures when it's not, I
> just want to check to see if that will be reliable when it's being
> started as well.
> -- Brian
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