IDS Forum

Re: 2 shared memory segments [18848 [18849] [18862

Posted By: brucemarchu@aol.com
Date: Tuesday, 2 February 2010, at 10:40 p.m.

In Response To: 2 shared memory segments (Brian Amstutz)

Hi Brian,

I have seen the SHMBASE parameter used with and without the "L". What=
do you see when you run the "onstat -g seg" command?

Since you also have the problem when rebooting the server you could consid=
er changing the order in which processes and applications are started on=
the computer after a reboot to have the Informix engine start up before=
a lot of other applications and processes. Take a look at the related st=
art up scripts such at the iniit.d and rc scripts. See what is being brou=
ght up before the Informix.

Regards,
Bruce

-----Original Message-----
From: Brian Amstutz <brian.amstutz@asburyseminary.edu>
To: ids@iiug.org
Sent: Mon, Feb 1, 2010 1:06 pm
Subject: RE: 2 shared memory segments [18848 [18849] [18862]

Thanks Bruce and Andy.=20
I have received this message both when only restarting Informix AND when=
=20
ebooting the entire server. I've used ipcs to try to find out what else=20
s using shared memory. I've identified a couple of apps and placed=20
nformix ahead of those in the startup order. However, there are some=20
pcs entries whose CPID or LPID do not show up in the current list of=20
rocesses - not sure if this is "normal" under HPUX or not???=20
'top' nearly always shows the 3 informix cpu vp's as the top 3 process -=
=20
t least all three within the top 8 processes.=20
I checked the machine notes and the only kernel parameter that wasn't set=
=20
igh enough was semmnu - I bumped it up from 256 to 2048 and will have to=
=20
find time to reboot the system. The recommendation for shmmax is=20
nywhere from 4Gb up to the maximum allowed. Currently, ours is set to=20
round 286Gb and the max allowed is 4096Gb. I may not understand exactly=20
ow shmmax is used but with only a 22Gb database, 8Gb RAM and 300Gb total=
=20
isk space - it seems like 286Gb for the max shared memory size should be=
=20
lenty large; however, I have bumped this up to approx 500Gb=20
Recommended SHMBASE is 0x0L - ours is set to 0x0 (minus the L) which I=20
THINK* is the same thing???=20
Nothing of interest found in the syslogs=20
Brian=20
>-----Original Message-----=20
From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of=20
brucemarchu@aol.com=20
Sent: Friday, January 29, 2010 8:36 PM=20
To: ids@iiug.org=20
Subject: Re: 2 shared memory segments [18848 [18849]=20
=20
Hi Brian,=20
=20
Here are several things to consider in addition to onconfig parameters:=20
1. There might be a problem with not enough available memory due to=20
emor=3D=20
y useage by applications that are running on the server. When you say=20
re=3D=20
start the server" do you mean just restarting the Informix engine, or=20
re=3D=20
you rebooting the actual physical machine? If your UNIX machine has acce=
=3D=20
ss to the "top" command you can run top with various flags to see what=20
ro=3D=20
cesses are using the most cpu's and the related memory being used.=20
2. Is the Informix engine crashing or are you doing an orderly shutdown=3D=
=20
and then a restart? If the Informix engine is hanging or crashing, then=3D=
=20
are you checking to make sure that all of the Informix memory segments=20
a=3D=20
ve been cleaned out before a restart. You can use ipcs and various flags=
=3D=20
such as ipcs -a, and ipcs -m from the UNIX prompt.=20
3. Check the Informix machine and documentation notes to see settings=20
or=3D=20
various UNIX kernel parameters relating to memory, and recheck your=20
urre=3D=20
nt settings. Make sure that you have at least the minimum values shown=20
o=3D=20
r memory related settings. Note that changing certain kernel parameters=20
i=3D=20
ght require a reboot of the physical machine. =3D20=20
4. Recheck the setting for the starting memory location SHMBASE in the=20
nc=3D=20
onfig file.=20
5. Recheck the UNIX system logs [ maybe at /var/adm/syslog or a similar=3D=
=20
location] to see if there are any error message regarding memory.=20
=20
Regards,=20
Bruce=20
=20
-----Original Message-----=20
From: Brian Amstutz <brian.amstutz@asburyseminary.edu>=20
To: ids@iiug.org=20
Sent: Fri, Jan 29, 2010 12:31 pm=20
Subject: 2 shared memory segments [18848]=20
=20
Informix 10.00.HC5 HP-UX 11i v2=3D20=20
Recently, I've started getting message like the following when I restart=
=3D=20
=3D20=20
he server=3D20=20
Could not create single shared memory segment with resident and=3D20=20
on-resident partitions. Proceeding to create 2 shared memory segments=3D20=
=20
nstead.=3D20=20
Sometimes, the server startup continues OK but other times the above=3D20=
=20
essage is followed by the following or similar message:=3D20=20
shmget: [ENOMEM][12]: key 52574802: out of shared memory, check system=20
ax=3D=20
=3D20=20
hared memory segment size=3D20=20
t_shm_init: can't create virtual segment=3D20=20
I'm guessing it's maybe a kernel parameter (shmmax?) issue but I haven't=
=3D=20
=3D20=20
it on the correct one to increase or how much to increase it by.=3D20=20
shmmax =3D3D 307200000000=3D20=20
HMVIRTSIZE =3D3D 321536=3D20=20
uffers =3D3D 350000 (2k)=3D20=20
Any ideas what to tune and what to tune it to?=3D20=20
Thanks!=3D20=20
Brian=3D20=20
=20
*************************************************************************=
=20
=3D=20
****=3D20=20
Forum Note: Use "Reply" to post a response in the discussion forum.=3D20=
=20
=20
=20
*************************************************************************=
=20
*****=20
Forum Note: Use "Reply" to post a response in the discussion forum.=20

**************************************************************************=
****=20
Forum Note: Use "Reply" to post a response in the discussion forum.=20

Messages In This Thread

• 2 shared memory segments
  Brian Amstutz -- Friday, 29 January 2010, at 3:31 p.m.
  • RE: 2 shared memory segments [18848 [18849]
    Andrew Lennard -- Monday, 1 February 2010, at 12:52 p.m.
  • RE: 2 shared memory segments [18848 [18849]
    Brian Amstutz -- Monday, 1 February 2010, at 4:06 p.m.
  • Re: 2 shared memory segments [18848 [18849] [18862
    brucemarchu@aol.com -- Tuesday, 2 February 2010, at 10:40 p.m.
  • RE: 2 shared memory segments [18848 [18849] [18862
    Brian Amstutz -- Wednesday, 3 February 2010, at 10:06 a.m.
  • RE: 2 shared memory segments [18848 [18849] [1....
    Brian Amstutz -- Friday, 5 February 2010, at 4:08 p.m.

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