Shared memory possibly not being used?

[mikeyintn]

I have 4 IP cameras. Two are 320x240 and the other two are 640x480.
I'm getting the monitors going red occasionally even after I've lowered the image buffer down to only 20 for each of the monitors and upped the shared mem max as as follows:

kernel.shmmax = 2935240000
kernel.shmall = 633810

From my calculations and after reading several posts it seems 220MB should be enough for these 4 cameras.

It seems like ZM isn't using my shared memory:
$ ipcs -m

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status

(nothing returned?)

Although it looks like it's available:
$ ipcs -l

------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 2866445
max total shared memory (kbytes) = 2535240
min seg size (bytes) = 1

I'm running 1.24.4 ZM compiled from source on Ubuntu 11.04 in a Virtualbox headless environment which I've allocated 4GB of RAM to. Could Virtualbox be part of the problem? Neither Ubuntu or the Virtualbox host seems to be taxed at all or the host computer.

I'm getting these kinds of errors in the logs when the monitor going red:

Aug 30 22:04:07 zmsrv zmc_m2[13129]: ERR [Got unexpected memory map file size 21197856, expected 18433032]

and

08/30/11 22:10:07.729694 zmdc[12043].ERR ['zmc -m 2' exited abnormally, exit status 255]

top - 22:30:50 up 11:40, 1 user, load average: 0.03, 0.07, 0.05
Tasks: 97 total, 2 running, 95 sleeping, 0 stopped, 0 zombie
Cpu(s): 5.3%us, 1.2%sy, 0.0%ni, 93.3%id, 0.1%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 4123936k total, 1100508k used, 3023428k free, 58560k buffers
Swap: 489468k total, 0k used, 489468k free, 794752k cached

Any suggestions what might be going on?

[bb99]

I believe by default 1.24.4 uses mmap (mapped memory) instead of shared.

[mikeyintn]

Ahh.. That did it!
Muchas gracias!