[ClusterLabs] Antw: [EXT] staggered resource start/stop

[Klaus Wenninger]

On 3/29/21 12:47 PM, Reid Wahl wrote:
>
>
> On Mon, Mar 29, 2021 at 3:35 AM Ulrich Windl 
> <Ulrich.Windl at rz.uni-regensburg.de 
> <mailto:Ulrich.Windl at rz.uni-regensburg.de>> wrote:
>
>     >>> d tbsky <tbskyd at gmail.com <mailto:tbskyd at gmail.com>> schrieb
>     am 29.03.2021 um 04:01 in Nachricht
>     <CAC6SzHLi0ufVhE3RM57e2V=t_mOmL5ECX8AY3gtcfGmOfKDaxg at mail.gmail.com
>     <mailto:t_mOmL5ECX8AY3gtcfGmOfKDaxg at mail.gmail.com>>:
>     > Hi:
>     >    since the vm start/stop at once will consume disk IO, I want to
>     > start/stop the vm
>     > one‑by‑one with delay.
>
>     I'm surprised that in these days of fast disks and SSDs this is
>     still an
>     issue.
>     Maybe don't delay the start, but limit concurrent starts.
>     Or maybe add some weak ordering between the VMs.
>
>
> kind=Serialize does this. It makes the resources start consecutively, 
> in no particular order. I added the comment about ocf:heartbeat:Delay 
> because D mentioned wanting a delay... but I don't see why it would be 
> necessary, if Serialize is used.
Wasn't the reason behind all of that the fact that VMs claim to be started
once the hypervisor is running (at least without any additional measures)
and that as a consequence starting them serialized wouldn't change much -
hence the delay (or something more elaborate that actually detects when
services in a VM are mostly up and not imposing lots of IO or whatever
load anymore).
>
>
>     >
>     >     search the email‑list I found the discussion
>     > https://oss.clusterlabs.org/pipermail/pacemaker/2013
>     <https://oss.clusterlabs.org/pipermail/pacemaker/2013>‑August/043128.html
>
>     >
>     >     now I am testing rhel8 with pacemaker 2.0.4. I wonder if
>     there are
>     > new methods to solve the problem. I search the document but didn't
>     > find new parameters for the job.
>     >
>     >     if possible I don't want to modify VirtualDomain RA which comes
>     > with standard rpm package. maybe I should write a new RA which
>     stagger
>     > the node utilization. but if I reset the node utilization when
>     cluster
>     > restart, there maybe a race condition.
>     >
>     >      thanks for help!
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>
> -- 
> Regards,
>
> Reid Wahl, RHCA
> Senior Software Maintenance Engineer, Red Hat
> CEE - Platform Support Delivery - ClusterHA
>
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