Re: What means: Shared memory realm does not exist?

Howard J. Rogers <howardjr_at_www.com> wrote:
> The absolute bog-standard typical cause as far as my (limited) Linux
> experience suggests is that your kernel parameters (sem and shmmax, usually)
> were not set to sufficiently high values; or (speaking from bitter
> experience) even when you remember to set them to the right values, you
> forget to re-boot the Linux box to allow them to take effect.

Actually, I have seen omission of tuning shmmax and sem to result in an error in the alert file, something to the effect of "unable to create shared mem segment of size....". Oracle still starts, but will not be able to use all of its buffer cache.

The tricky thing is that when you set these to the right values via the /proc/sys/... interface, they take effect immediately.... but are reset when you reboot the box :(. You must script somewhere to update them when the box reboots.

I have 512MB max SGA. This is a line that I put in the local boot file...

echo "512 * 1024^2" | bc > /proc/sys/kernel/shmmax

(kernel 2.4.x)

JT.

>> Received on Sat Sep 15 2001 - 22:35:03 CDT