[ClusterLabs] Antw: Re: Antw: Re: Issue with DB2 HADR cluster

[Ulrich Windl]

>>> Valentin Vidic <Valentin.Vidic at CARNet.hr> schrieb am 03.04.2019 um 09:26
in
Nachricht <20190403072602.GW9348 at gavran.carpriv.carnet.hr>:
> On Wed, Apr 03, 2019 at 09:13:58AM +0200, Ulrich Windl wrote:
>> I'm surprised: Once sbd writes the fence command, it usually takes
>> less than 3 seconds until the victim is dead. If you power off a
>> server, the PDU still may have one or two seconds "power reserve", so
>> the host may not be down immediately. Besides of that power‑cycles are
>> additional stress for the hardware...
>> 
>> So maybe you want to explain why and how much faster IPMI and PDU fencing 
> are.
> 
> SBD is slow for me too. Since it doesn't have a way to confirm the kill
> it needs to wait for various timeouts and these can be quite high. For
> example the IBM storage timeouts require this setup:
> 
>   Timeout (watchdog) : 130
>   Timeout (msgwait)  : 270

Reminds me of a 30 minute SCSI timeout for the rewind command to a magnetic
tape...
SCSI still has (AFAIK) 60s disk timeouts, but actually if a disk's response
time exceeds 3 seconds on reads, it's time to replace it. I don't know what the
IBM storage system does behind the scenes, but the timeout seems excessively
slow.

> 
> On the same cluster IPMI fence executes in a second or two, but requires
> network connectivity.
> 
> ‑‑ 
> Valentin
> _______________________________________________
> Manage your subscription:
> https://lists.clusterlabs.org/mailman/listinfo/users 
> 
> ClusterLabs home: https://www.clusterlabs.org/