[Veritas-bu] status 89 out of the blue

Richard.Hall Richard.Hall at ingenta.com
Wed Mar 23 10:24:25 CST 2005


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.


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