what is the biggest shared memory segment on HP-UX 64-bit? I need
allocate one single segmen. And maybe you have information about AIX
servers too.

Thanks.

Petronenko Denis wrote:
> what is the biggest shared memory segment on HP-UX 64-bit? I need
> allocate one single segmen. And maybe you have information about AIX
> servers too.

The kernel tunable shmmax determines the absolute bound (there are
address space layout limitations, but on PA-RISC the shmmax tunable
is bounded by the 64-bit address space limit, and on IPF it is well
below that limit).

http://docs.hp.com/en/B2355-60127/shmmax.5.html for the 11.11 man
page, if you're on 11.23 just do "man shmmax" - the man pages were
shipped with that release.

That's the theoretical bound, mind you.

In practice, you're obviously bounded by the available shared
address space (this is the global 32-bit / 64-bit shared
quadrant (top 1Gb of the 4Gb address space) plus the 64-bit
only shared areas, and you must have sufficient swap space
to cover the virtual address space [just like any other
virtual object on HP-UX]. Those limitations usually kick in
before high values of shmmax. (shmget will return ENOMEM if
the problem is being out of resources, EINVAL if you're
violating the shmmax bounds.. man shmget for full details).

AIX I believe has a similar tunable, don't know what other
restrictions might come into play.

Don