ADSM-L

Re: People running OS/390 TSM servers - maybe for the development guys......

2002-03-20 07:28:59
Subject: Re: People running OS/390 TSM servers - maybe for the development guys......
From: "Stumpf, Joachim" <joachim.stumpf AT DATEV DOT DE>
Date: Wed, 20 Mar 2002 12:26:32 -0000
Hi Christo,

we are running TSM-Server 4.1.5 on OS/390.
Im not very familiar with this OS/390- MVS- Stuff, but I can tell you that we 
have 10 TSM-Server running at 1 LPAR.
We named the tasks TADSM01-TADSM10. 
The issue to do so was that we only wanted small databases.
Now our dbs are from 7GB - 12GB.

-- 
regards / Mit freundlichen Gruessen
regards / Mit freundlichen Gruessen
Joachim Stumpf
Datev eG
Nuremberg - Germany
      

Christo Heuer <christoh AT ABSA.CO DOT ZA> (Mittwoch, 20. März 2002, 11:55:08, 
CET):

> Hi all,
> 
> OK - For those of you that does not know anything about
> OS/390 or don't run TSM servers on OS/390 this might be
> very boring and maybe a bit cryptic - ignore or just
> read for the fun.
> Now for the people that still run OS/390 TSM servers:
> 
> I have always had my doubts about the scalability of
> OS/390 when it comes to a TSM server.
> Some of you might have seen me posting last year and early
> this year about the size of your TSM environment and if
> you are happy with the performance of TSM on OS/390 - only
> one guy answered giving me specs on the environment they
> run(Thanks to William Colwell), but other than that
> most people said they moved off OS/390 and are now
> running AIX or Sun or even Win2K servers.
> William described their environment as an 80 Mips
> processor box and a 166Gig db 88% used - and on top
> of all that he has good performance from this.
> 
> Our environment is a 38 Gig db 80% used and we have
> crappy performance. Now in Adsm V3 a new parameter
> was introduced called MPTHREADING YES or NO. What
> this does is tell TSM that it can start multiple
> TCB's on multiple CP's - if you have multiple CP's
> on your box.
> Now we enabled this and noticed that TSM gets its
> knickers in a knot when there are too many things
> happening and the system is CPU constrained. In
> WLM it is guarenteed to get CPU and in WDM you can
> see that about 30% of the time it is delayed for
> CPU. What we have done now in Omegamon is to check
> how many work each of the TCB's does and then try
> and figure out why TSM would perform crappy even though
> it is getting about 50% of the total box.
> Now - here comes the part where development might
> be able to shed some light:
> 
> The TCB called dsmserv (the server task), has a
> lmod caled IEANUC01 that has a CSECT of IGVGPVT
> that uses about 90-95% of all the CPU cycles - remember
> that this is one TCB assigned to one CP.
> On further investigation our IBM'er came back and said
> this IGVGPVT part controls getmain/freemain's for TSM.
> Now here comes the question:
> How can TSM be using 90% of a CP by just doing getmain/freemain
> and all the other TCB's that has a CP allocated just sit
> and wait for getmain/freemain's. This looks like a
> serious scalability issue with TSM on a multiple
> CP environment. According to our performance and MVS
> guys the only way we are going to squeeze more juice
> out of our OS/390 system with TSM is to split the
> workload of TSM and run two TSM servers on one LPAR
> or upgrade each CP to a more powerfull CP.
> Is this in line with development, and the way it should work?
> 
> Thanks
> Christo Heuer
> ASBA Bank
> Johannesburg
> SOUTH AFRICA
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