SHMMAX and Oracle 8.1.7.1

[David Snider]

We are running Oracle 8.1.7.1 on HP-UX 11.x 64-bit. I believe the Oracle version is 32-bit. My question is, I noticed that Oracle is creating 2 Shared Memory Segments, on is exactly 1GB, the other is around 500MB.. My SHMMAX parameter was set to 1GB, I have since changed it to 2GB.. However, Oracle is still creating two shared memory segments. Has anyone else run into this? I have an Oracle8 Performance and tuning book that says for performance reasons, Oracle should only have one shared memory segment.. Any help is appreciated.. ;-)

[Vincenzo Restuccia]

Try http://www.dutchworks.nl/htbin/hpsysadmin?h=3&dn=58635&q=SHMMAX%20and%20Oracle%208.1.7.1&fh

[Pedro Sousa]

Hi David,
Note that you can only increase shmmax to a maximum value of 1792 Mbytes!
Are you sure that Oracle is using 2 shared memory segments?
use "ipcs -a"

[MANOJ SRIVASTAVA]

No the limitation of 32 bit applications are that only . You cannot access more than 1.8 GB , so the operating system does that and you need to put SHMAX at 1.0 GB only .

Manoj Srivastav

[David Snider]

Thanks James,

According to the article you directed me to, it is possible for Oracle to use more than 1.75 GB of RAM.. But I need the Memory Windows product.. Is this something that must be purchased? Or can I download it..

Pedro,

Here is a snippet of my ipcs command
#ipcs -mopb
IPC status from /dev/kmem as of Fri May 11 09:29:13 2001
T ID KEY MODE OWNER GROUP NATTCH SEGSZ
Shared Memory:
m 155 0x00000000 --rw-rw---- oracle dba 9 1073741824
m 156 0x5bc5a610 --rw-rw---- oracle dba 9 518119424

One segment is exactly 1GB, the other is about 518MB..

Also, according to HP, the maximum setting for SHMMAX in HP-UX 64-bit is 1 TB.. not 1792 MB..

Check out this link for more info..

http://docs.hp.com/hpux/onlinedocs/os/KCparam.ShMmax.html