IDS Forum

Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b

Posted By: Art Kagel
Date: Thursday, 15 May 2014, at 11:22 a.m.

In Response To: Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b (JAN-PETER SEIFERT)

Peter:

One thing to note is that in 11.70 IBM changed the way that the
VP_MEMORY_CACHE_KB works. In 11.50 the value configured for this parameter
is fixed and permanent or static. If a VP needed more memory than the
VPCACHE setting it would get that from the central memory pool and release
the excess when it was finished with it.

In 11.70 the value became a starting point with the engine free to increase
the maximum amount cached in each CPU VP dynamically. Unfortunately once
memory is added to the CPU VPCACHE it is NEVER released back to the central
memory pool so if queries need memory for sorting or grouping etc. then
engine may have to add more virtual segments.

So, it may be that the memory segments being added are needed permanently
for large complex queries, but it may just be the new VPCACHE behavior. In
11.70.xC8+ and 12.10 the VP_CACHE_MEMORY_KB was extended to take a second
argument of either ,STATIC or ,DYNAMIC (so VP_CACHE_MEMORY_KB 1024,STATIC
for example). The latter is the new default behavior and ,STATIC restored
the older v11.50 behavior. So you may want to upgrade so you can set the
cache back to STATIC behaviors.

Once test to see if it may be the VPCACHE is to try to run onmode -F and
see if any of the used memory in the virtual segments is freed. If the
memory was being used for large queries that have completed, the -F will
gather all free bits and pieces of virtual memory together and all the free
memory together and free any unneeded virtual segments. If the memory has
been assigned to the VPCACHE then it isn't free and no segments will be
released.

Art

Art S. Kagel, Principal Consultant
ASK Database Management

Blog: http://informix-myview.blogspot.com/

Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on the IIUG, nor any other organization with which I am
associated either explicitly, implicitly, or by inference. Neither do
those opinions reflect those of other individuals affiliated with any
entity with which I am affiliated nor those of the entities themselves.

On Thu, May 15, 2014 at 10:52 AM, JAN-PETER SEIFERT <seifert@his.de> wrote:

> Hello,
>
> thank you very much for your fast reply!
>
> > Have a look at onstat -g seg and ipcs -ma.
>
> > A starting point would be to see what all the "V"'s add up to from
> onstat -g
> seg and set SHMVIRTSIZE to that.
>
> Currently those are set in the onconfig file to:
> SHMVIRTSIZE 262144
> SHMADD 32768
>
> onstat -g seg shows 95 virtual segments that have been added:
>
> -----------------------------------------------------------------------------
> IBM Informix Dynamic Server Version 11.70.FC7 -- On-Line -- Up 21:53:00 --
> 4042644 Kbytes
>
> Segment Summary:
> id key addr size ovhd class blkused blkfree
> 0 52564801 44000000 682450944 8430968 R 166613 1
> 32769 52564802 6cad6000 268435456 3147384 V 64909 627
> 65538 52564803 7cad6000 1110016 14328 M 270 1
> 98307 52564804 7cbe5000 33554432 394728 V 8192 0
> 131076 52564805 7ebe5000 33554432 394728 V 8192 0
> ..
> ..
> ..
> 3113055 52564860 134be5000 33554432 394728 V 8192 0
> 3145824 52564861 136be5000 33554432 394728 V 8191 1
> 3178593 52564862 138be5000 33554432 394728 V 543 7649
> Total: - - 4139667456 - - 1002373 8288
>
> -----------------------------------------------------------------------------
> Should I really set SHMVIRTSIZE to 3375104 then?
>
> I wonder what is adding so much virtual segments automatically around 3 PM
> after each server restart. Today they have been added from 14:56:36 until
> 14:59:58.
>
> According to OAT these tasks could be responsible:
> ----------------------------------------------------------------------
> mon_users 3672 0.02 100.22 2014-05-15 14:56:32 Success
> mon_low_storage 14557 0.00 23.09 2014-05-15 14:56:32 Success
> check_backup 616 0.02 16.69 2014-05-15 14:56:32 Success
> Alert Cleanup 616 0.03 22.75 2014-05-15 14:56:32 Success
> Job Results Cleanup 616 0.01 7.41 2014-05-15 14:56:32 Success
> mon_memory_system 7336 0.01 94.41 2014-05-15 14:56:34 Success
> mon_checkpoint 14660 0.01 219.92 2014-05-15 14:56:34 Success
> mon_table_profile 1229 1.49 1833.08 2014-05-15 14:56:34 Success
> mon_profile 3672 0.01 61.38 2014-05-15 14:56:34 Success
> mon_command_history 616 0.00 1.29 2014-05-15 14:56:34 Success
> mon_vps 3672 0.00 22.42 2014-05-15 14:56:34 Success
> mon_table_names 616 32.60 20083.29 2014-05-15 14:57:28 Success
> Low Memory Reconfig 14660 0.00 72.84 2014-05-15 15:03:25 Success
> ----------------------------------------------------------------------
>
> I guess it must be 'Low Memory Reconfig', but then 'Last Run Time' means
> the
> last time the task has been finished running?
>
> > 2. The error was ENOSPC - I would suggest you look swap configuration.
>
> > How much swap is allocated to this host?
>
> swapon -s:
> Filename Type Size Used Priority
> /dev/sda1 partition 7811068 188 -1
>
> > What is "RESIDENT" set to in the $ONCONFIG?
> RESIDENT 0
>
> I'll have a look whether Ubuntu supports forcing residency.
>
> > Have you really configured this instance to "work within resources that
> are
> available"?
>
> I guess not really, because of the error. After the problem appeared the
> first
> time I set SHMTOTAL to a fixed value and it didn't help. So it's currently
> back at 0. I guess it was set too low. The current official system
> requirements aren't that high though:
> http://www-01.ibm.com/support/docview.wss?rs=630&uid=swg27013343
>
> > 3.
>
> http://www.linuxquestions.org/questions/linux-newbie-8/shmmax-in-ubuntu-860206/
> .... SHMMAX is probably the kernel parameter you are looking for.
>
> It's currently set to 4187361280 - but considering that Informix is using
> 4042644 Kbytes according to 'onstat -' already 6281041920 might be better?
>
> Thank you very much!
>
> Best regards,
>
> Peter Seifert
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--001a11340950fa2f6904f971dba4

Messages In This Thread

• shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 bit
  JAN-PETER SEIFERT -- Thursday, 15 May 2014, at 5:44 a.m.
  • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
    Art Kagel -- Thursday, 15 May 2014, at 6:41 a.m.
    • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
      JAN-PETER SEIFERT -- Thursday, 15 May 2014, at 8:34 a.m.
  • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
    JON RITSON -- Thursday, 15 May 2014, at 6:42 a.m.
    • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
      JAN-PETER SEIFERT -- Thursday, 15 May 2014, at 10:52 a.m.
      • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
        Art Kagel -- Thursday, 15 May 2014, at 11:22 a.m.
        • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
          JAN-PETER SEIFERT -- Friday, 16 May 2014, at 4:46 a.m.
          • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
            Art Kagel -- Friday, 16 May 2014, at 6:34 a.m.
            • Re: shmget ENOSPC Informix 11.70FC7 on Ubuntu 64 b
              JAN-PETER SEIFERT -- Friday, 16 May 2014, at 7:19 a.m.

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