topic Re: problems when placing shared memory in Operating System - HP-UX

problems when placing shared memory

Harrison M Leal — Wed, 16 Apr 2003 12:22:50 GMT

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

Re: problems when placing shared memory

Zafar A. Mohammed_1 — Wed, 16 Apr 2003 12:28:34 GMT

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

Thanks
Zafar

Re: problems when placing shared memory

Michael Steele_2 — Wed, 16 Apr 2003 14:04:07 GMT

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?

Re: problems when placing shared memory

Harrison M Leal — Wed, 16 Apr 2003 16:59:33 GMT

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

Re: problems when placing shared memory

Zafar A. Mohammed_1 — Wed, 16 Apr 2003 17:04:34 GMT

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

Thanks
Zafar

Re: problems when placing shared memory

Bill Hassell — Wed, 16 Apr 2003 17:53:47 GMT

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/