Hi Jim,
correction - we have z14 not z114
 .. .not sure why I keep calling our z14 z114 ;)  We have z14

We have 16 IFLs in total shared across 5 z/VM lparps but really there is
literally nothing running in there yet beside this one huge VM which has 10
IFLs configured. We have plenty of spare memory left and this one VM has
150G configured. It is about the same as what they had for this database
when it was on the AIX. This number has been calculated by DBAs and it
seems ok. I am not sure how to tell if DB2 is happy with what it has or
not, but the linux OS is definitely not starving for memory.

that p7 was 9117-MMD. And I just found that it was had EC set to 10 but it
could pull up to 15 processors. I am not sure how that works over there.



On Tue, Nov 3, 2020 at 10:58 AM Jim Elliott <jlelliot...@gmail.com> wrote:

> Gregory:
>
> Do you have a z114 with 10 IFLs? That is the maximum number of IFLs
> available on a z114 (2818-M10) and would be unusual. Is this a single z/VM
> LPAR? How much memory is on the z114 (and in this LPAR)? Also, what was the
> specific MT/Model for the P7 box?
>
> If you were to compare a 12-core Power 730 (8231-E2C) to a 10 IFL z114 the
> Power system has 1.4 to 2.0 times the capacity of the z114.
>
> Jim Elliott
> Senior IT Consultant - GlassHouse Systems Inc.
>
>
> On Tue, Nov 3, 2020 at 8:47 AM Grzegorz Powiedziuk <gpowiedz...@gmail.com>
> wrote:
>
> > Hi, I could use some ideas. We moved a huge db2 from old p7 aix to rhel7
> on
> > Z and we are having big performance issues.
> > Same memory, CPU number is down from 12 to 10.  Although they had
> > multithreading ON so they saw more "cpus" We have faster disks (moved to
> > flash), faster FCP cards and faster network adapters.
> > We are running on z114 and at this point that is practically the only VM
> > running with IFLs on this box.
> >
> > It seems that when "jobs" run on their own, they finish faster than what
> > they were getting on AIX.
> > But problems start if there is more than we can chew. So either few jobs
> > running at the same time or some reorgs running in the database.
> >
> > Load average goes to 150-200, cpus are at 100%  (kernel time can go to
> > 20-30% ) but no iowaits.
> > Plenty of memory available.
> > At this point everything becomes extremely slow, people are starting
> having
> > problems with connecting to db2 (annd sshing), basically it becomes a
> > nightmare
> >
> > This db2 is massive (30+TB) and it is a multinode configuration (17 nodes
> > running on the same host). We moved it like this 1:1 from that old AIX.
> >
> > DB2 is running on the ext4 filesystem (Actually a huge number of
> > filesystems- each NODE is a separate logical volume). Separate for logs,
> > data.
> >
> > If this continues like this, we will add 2 cpus but I have a feeling that
> > it will not make much difference.
> >
> > I know that we end up with a massive number of processes and a massive
> > number of file descriptors (lsof sice it shows also threads now, is
> > practically useless - it would run for way too long - 10-30 minutes
> > probably) .
> >
> > A snapshot from just now:
> >
> > top - 08:37:50 up 11 days, 12:04, 28 users,  load average: 188.29,
> 151.07,
> > 133.54
> > Tasks: 1843 total,  11 running, 1832 sleeping,   0 stopped,   0 zombie
> > %Cpu0  : 76.3 us, 16.6 sy,  0.0 ni,  0.0 id,  0.0 wa,  1.0 hi,  3.2 si,
> >  2.9 st
> > %Cpu1  : 66.1 us, 31.3 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.6 hi,  1.3 si,
> >  0.6 st
> > %Cpu2  : 66.9 us, 31.2 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.3 hi,  1.3 si,
> >  0.3 st
> > %Cpu3  : 74.7 us, 23.4 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.3 hi,  1.3 si,
> >  0.3 st
> > %Cpu4  : 86.7 us, 10.7 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.6 hi,  1.3 si,
> >  0.6 st
> > %Cpu5  : 83.8 us, 13.6 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.6 hi,  1.6 si,
> >  0.3 st
> > %Cpu6  : 81.6 us, 15.2 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.6 hi,  1.9 si,
> >  0.6 st
> > %Cpu7  : 70.6 us, 26.2 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.6 hi,  1.9 si,
> >  0.6 st
> > %Cpu8  : 70.5 us, 26.6 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.6 hi,  1.6 si,
> >  0.6 st
> > %Cpu9  : 84.1 us, 13.6 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.3 hi,  1.3 si,
> >  0.6 st
> > KiB Mem : 15424256+total,  1069280 free, 18452168 used,
> 13472112+buff/cache
> > KiB Swap: 52305904 total, 51231216 free,  1074688 used. 17399028 avail
> Mem
> >
> > Where  can I look for potential relief? Everyone was hoping for a better
> > performance not worse.I am hoping that there is something we can tweak to
> > make this better.
> > I will appreciate any ideas!
> > thanks
> > Gregory
> >
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