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How does PSS affect the parallelism unit?
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How does PSS affect the parallelism unit?

Posted by George Sinclair - NOAA Federal 
George Sinclair - NOAA Federal
How does PSS affect the parallelism unit?
October 05, 2019 02:59AM
If 'parallel save streams per save set' is enabled then does each stream
count as a parallelism unit in terms of the client or group parallelism
and/or target sessions?

For example, I had target sessions, client parallelism and group
parallelism all set to 8. I ran a backup wherein the client resource
specified two save sets, and it started 8 chunks or streams (4 per save
set with the '<#>' naming convention). Next, I changed the group
parallelism to 4, and reran the backup, and again, it runs 8 chunks. Why
would it do that if each counts as a parallelism unit of 1? I then
changed the target sessions to 4, and reran it. This time it only ran 4
chunks to the drive and then loaded another tape and sent the other 4
chunks to that drive, although neither save set's streams were solely
apportioned to the same drive.

I also noticed that even though the client parallelism was set to 8,
there were times when one or two other groups, containing this client,
were concurrently running during this test, so at any given time, there
may have been 10-12 save processes running on the client, if you include
the 8 streams from the PSS backup. Therefore, I'm unclear if these are
counted as part of the parallelism, or if the parallelism is not an
absolute limit, but target sessions is?

Also, is the client parallelism the maximum number of concurrent save
processes that the client can have running at any given time or instead
the maximum number that any given group (backup) for the client can run?

I'm inclined to say that only the server parallelism and the target
sessions are absolute, which would explain what I observed, but I'm not
confident.

Thanks.

George

--
George Sinclair
Voice: (301) 713-4921
- The preceding message is personal and does not reflect any official or unofficial position of the United States Department of Commerce -
- Any opinions expressed in this message are NOT those of the US Govt. -


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Preston de Guise
Re: How does PSS affect the parallelism unit?
October 05, 2019 10:59PM
Hi George,


> On 5 Oct 2019, at 12:34 pm, George Sinclair - NOAA Federal <000001bd925b8f5e-dmarc-request@LISTSERV.TEMPLE.EDU> wrote:
>
> If 'parallel save streams per save set' is enabled then does each stream count as a parallelism unit in terms of the client or group parallelism and/or target sessions?
>
> For example, I had target sessions, client parallelism and group parallelism all set to 8. I ran a backup wherein the client resource specified two save sets, and it started 8 chunks or streams (4 per save set with the '<#>' naming convention). Next, I changed the group parallelism to 4, and reran the backup, and again, it runs 8 chunks. Why would it do that if each counts as a parallelism unit of 1? I then changed the target sessions to 4, and reran it. This time it only ran 4 chunks to the drive and then loaded another tape and sent the other 4 chunks to that drive, although neither save set's streams were solely apportioned to the same drive.
>
> I also noticed that even though the client parallelism was set to 8, there were times when one or two other groups, containing this client, were concurrently running during this test, so at any given time, there may have been 10-12 save processes running on the client, if you include the 8 streams from the PSS backup. Therefore, I'm unclear if these are counted as part of the parallelism, or if the parallelism is not an absolute limit, but target sessions is?

What version of NetWorker are you using? In theory yes, the different parallelism settings (especially client parallelism) should be adhered to, so I wonder if there’s an issue with the version(s) you’re using?

> Also, is the client parallelism the maximum number of concurrent save processes that the client can have running at any given time or instead the maximum number that any given group (backup) for the client can run?
>
> I'm inclined to say that only the server parallelism and the target sessions are absolute, which would explain what I observed, but I'm not confident.
>
> Thanks.
>
> George
>
> --
> George Sinclair
> Voice: (301) 713-4921
> - The preceding message is personal and does not reflect any official or unofficial position of the United States Department of Commerce -
> - Any opinions expressed in this message are NOT those of the US Govt. -
>
>
> --
> This list is hosted as a public service at Temple University by Stan Horwitz
> If you wish to sign off this list or adjust your subscription settings, please do so via http://listserv.temple.edu/archives/emc-dataprotection-l.html
> If you have any questions regarding management of this list, please send email to owner-emc-dataprotection-l@listserv.temple.edu


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