[gpfsug-discuss] GPFS+TSM+HSM: staging vs. migration priority

[Jaime Pinto]

Thanks for the suggestions Dominic

I remember playing around with premigrated files at the time, and that  
was not satisfactory.

What we are looking for is a configuration based parameter what will  
basically break out of the "transparency for the user" mode, and not  
perform any further recalling, period, if|when the file system  
occupancy is above a certain threshold (98%). We would not mind if  
instead gpfs would issue a preemptive "disk full" error message to any  
user/app/job relying on those files to be recalled, so migration on  
demand will have a chance to be performance. What we prefer is to swap  
precedence, ie, any migration requests would be executed ahead of any  
recalls, at least until a certain amount of free space on the file  
system has been cleared.

It's really important that this type of feature is present, for us to  
reconsider the TSM version of HSM as a solution. It's not clear from  
the manual that this can be accomplish in some fashion.

Thanks
Jaime

Quoting Dominic Mueller-Wicke01 <dominic.mueller at de.ibm.com>:

>
>
> Hi,
>
> in all cases a recall request will be handled transparent for the user at
> the time a migrated files is accessed. This can't be prevented and has two
> down sides: a) the space used in the file system increases and b) random
> access to storage media in the Spectrum Protect server happens. With newer
> versions of Spectrum Protect for Space Management a so called tape
> optimized recall method is available that can reduce the impact to the
> system (especially Spectrum Protect server).
> If the problem was that the file system went out of space at the time the
> recalls came in I would recommend to reduce the threshold settings for the
> file system and increase the number of premigrated files. This will allow
> to free space very quickly if needed. If you didn't use the policy based
> threshold migration so far I recommend to use it. This method is
> significant faster compared to the classical HSM based threshold migration
> approach.
>
> Greetings, Dominic.
>
> ______________________________________________________________________________________________________________
>
> Dominic Mueller-Wicke | IBM Spectrum Protect Development | Technical Lead |
> +49 7034 64 32794 | dominic.mueller at de.ibm.com
>
> Vorsitzende des Aufsichtsrats: Martina Koederitz; Geschäftsführung: Dirk
> Wittkopp
> Sitz der Gesellschaft: Böblingen; Registergericht: Amtsgericht Stuttgart,
> HRB 243294
> ----- Forwarded by Dominic Mueller-Wicke01/Germany/IBM on 08.03.2016 18:21
> -----
>
> From:	Jaime Pinto <pinto at scinet.utoronto.ca>
> To:	gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
> Date:	08.03.2016 17:36
> Subject:	[gpfsug-discuss] GPFS+TSM+HSM: staging vs. migration priority
> Sent by:	gpfsug-discuss-bounces at spectrumscale.org
>
>
>
> I'm wondering whether the new version of the "Spectrum Suite" will
> allow us set the priority of the HSM migration to be higher than
> staging.
>
>
> I ask this because back in 2011 when we were still using Tivoli HSM
> with GPFS, during mixed requests for migration and staging operations,
> we had a very annoying behavior in which the staging would always take
> precedence over migration. The end-result was that the GPFS would fill
> up to 100% and induce a deadlock on the cluster, unless we identified
> all the user driven stage requests in time, and killed them all. We
> contacted IBM support a few times asking for a way fix this, and were
> told it was built into TSM. Back then we gave up IBM's HSM primarily
> for this reason, although performance was also a consideration (more
> to this on another post).
>
> We are now reconsidering HSM for a new deployment, however only if
> this issue has been resolved (among a few others).
>
> What has been some of the experience out there?
>
> Thanks
> Jaime
>
>
>
>
> ---
> Jaime Pinto
> SciNet HPC Consortium  - Compute/Calcul Canada
> www.scinet.utoronto.ca - www.computecanada.org
> University of Toronto
> 256 McCaul Street, Room 235
> Toronto, ON, M5T1W5
> P: 416-978-2755
> C: 416-505-1477
>
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Jaime Pinto
SciNet HPC Consortium  - Compute/Calcul Canada
www.scinet.utoronto.ca - www.computecanada.org
University of Toronto
256 McCaul Street, Room 235
Toronto, ON, M5T1W5
P: 416-978-2755
C: 416-505-1477

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