problems when placing shared memory

[Harrison M Leal]

I have three servers in a high availability cluster , where I have one instance of sybase in each of them, I have defined 1 Gb of
shared memory for each instace of sybase, I have defined 2,5 Gb of shared memory for each server and there are 2 Gb of
physical memory in each one . My problem is :

When my server goes to another server the log show us the message "Cannot allocate shared memory" ( this message from of sybase )

When I verify my server , it has shared memory available.

Harrison M Leal

[Zafar A. Mohammed_1]

Did you check the Sybase Machine/Release Notes or check the Sybase Bug Fix/Open Release Notes

Thanks
Zafar

[Michael Steele_2]

Was a dump in progress?

See anything with ipcs?

ipcs -a

Remove leftovers with ipcrm:

ipcrm -m mid1 -m mid2 ... -s sid1 -s sid2 ...

Is SYBMULTBUF still running?

[Harrison M Leal]

When I run command the ipcs -am , don't have nothing that it is allocated much memory , the problem don't is this.

[Zafar A. Mohammed_1]

Is there any Memory Leak problem with Sybase Version or some bugs with this version. Open the case with Sybase.

Thanks
Zafar

[Bill Hassell · Accepted solution]

If Sybase is running as a 32bit program, then the shared memory map has become fragmented by other processes stopping and starting. 32bit program are severely limited in shared memory and must share a single map regardless of how much total RAM you may have. There is no specific location in RAM for shared memory, just a set of pointers. BUT: each shared memory segment requested by the program MUST be contiguous. While you may have 500 megs of free RAM in the shared memory map, perhaps none of the spaces are larger than 100megs.

Get a copy of the shminfo program so you can see how badly fragmented this area has become. If you cannot run a 64bit version of the program, you'll have to reboot or somehow shutdown all the processes using shared memory and restart them in the right order. Get shminfo from:

ftp://contrib:9unsupp8@hprc.external.hp.com/sysadmin/programs/shminfo/