Veritas-bu

[Veritas-bu] status 89 out of the blue

2005-03-23 11:47:00
Subject: [Veritas-bu] status 89 out of the blue
From: Bill_Jorgensen AT csgsystems DOT com (Jorgensen, Bill)
Date: Wed, 23 Mar 2005 09:47:00 -0700
Dave:

Good eyes Richard! Yikes! That would mean the default of one meg is
defined (you would need to confirm). As for NBU's intelligence to fix
the IPC shortage? Dicey at best. It does a ton of things, but fixing IPC
shortages like Oracle in Richard's example? Highly unlikely. Edit the
/etc/system file and reboot...

--------------------------------------------------------
     Bill Jorgensen
     CSG Systems, Inc.
     (w) 303.200.3282
     (p) 303.947.9733
--------------------------------------------------------
     UNIX... Spoken with hushed and
     reverent tones.
--------------------------------------------------------

-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of
Richard.Hall
Sent: Wednesday, March 23, 2005 9:24 AM
To: dave.markham AT fjserv DOT net
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] status 89 out of the blue

Dave,

On Wed, 23 Mar 2005, Jorgensen, Bill wrote:

> Dave:
>
> As I read your value for shmmax it seems to be 16MB of shared memory.

I believe Bill reads wrong, in two respects:-

1) You have the setting commented out for some reason!

> *set shmsys:shminfo_shmmax=16777216
> *set shmsys:shminfo_shmin=1
> set shmsys:shminfo_shmmni=220
> set shmsys:shminfo_shmseg=100

2) AIUI it only defines the _maximum_ size of a _single_ shared memory
segment, not the total size of all shared segments in the system. Bill's
output appears to confirm that:-

> root[prod-backup:/]# sysdef -i | grep -i memory
> * IPC Shared Memory
> 1073741824      max shared memory segment size (SHMMAX)

As an extreme example, we had a badly misconfigured system running
Oracle.
IIRC shmsys:shminfo_shmmax was set at 4 Mb instead of 4 Gb (or something
daft like that). Oracle compensated by creating a _large_ number of 4 Mb
shared segments, sufficient to get to the configured size of its SGA :-)
Once corrected, it created a single large segment.

I have no idea whether NBU is equally, er, intelligent.

You need to look at 'ipcs -ma' to find out what is really in use.

HTH,
 Richard


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