Shared memory problem

[Gordon_3]

HI all,

I have encounter some issues about the shared memory usage, as u seen, below mainly have 3 apps running which require shared memory, Oracle, Sybase, and one called Datastage ( dsadm id ). I hit the problem of , if Sybase startup before Datastage, then Datastage will fail to startup, but if I reverse the sequence , both can start. Knowing that it's due to contigueous shared memory requirement, right? I just wanna will increase the shmax can ease this situation? Our config is quite large I think, total physical is 8G with now shmax is 3G....

Gordon

hkgdev2:/#ipcs -m
IPC status from /dev/kmem as of Fri Sep 27 09:59:00 2002
T ID KEY MODE OWNER GROUP
Shared Memory:
m 0 0x411c17c1 --rw-rw-rw- root root
m 1 0x4e0c0002 --rw-rw-rw- root root
m 2 0x41201f8d --rw-rw-rw- root root
m 18435 0x0c6629c9 --rw-r----- root sys
m 4 0x06347849 --rw-rw-rw- root root
m 1029 0xffffffff --rw-r--rw- root root
m 18438 0xdaec9611 --rw-rw-rw- root dstage
m 99335 0x6e3807e6 --rw------- sybase sybase
m 1032 0x6e380007 --rw------- sybase sybase
m 3081 0x6e38036f --rw------- sybase sybase
m 10 0xd502b578 --rw-r----- oracle oinstall
m 11 0xb0ed6e7c --rw-r----- root sys
m 15372 0x6e38037c --rw------- sybase sybase
m 248845 0xdaebd3bb --rw------- dsadm dstage
m 242702 0x6e380386 --rw------- sybase sybase
m 70672 0x00000000 --rw------- sybase sybase

[John Poff · Accepted solution]

Hi Gordon,

Are you running 32-bit apps? What version of HP-UX are you running?

There are some things you can do. Here are a couple of threads discussing shared memory. The first one deals with the contiguous problem, which sounds like what you are running into.


http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x5825543254bfd611abdb0090277a778c,00.html

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x1382107d277ad611abdb0090277a778c,00.html


JP

[Gordon_3]

HI John,

Thx for yr info, however, all the OS, Sybase, Datastage is runnning 64bit, so will it be other case else? Also can increase shmax ease this situation?

Gordon

[Ravi_8]

Hi Gordon

Apart from increasing shmmax consider increasing shmseg also, which increases the segment size of shared memory

[Gordon_3]

Hi Ravi,

My current shmseg setting is 512, is it too small?

Gordon

[Ravi_8]

Hi,

In one of my server running 2 oracle instances and a sybase instance shared memory values are as set below, running very well.

# kmtune|grep shm
shmem 1
shmmax 4294967295
shmmni 1024
shmseg 1024

[Ravi_8]

Hi (again)

ofcourse the memory is only 1GB

[Gordon_3]

Hi Ravi,

Not quite understand, u mean u have just 1G physical but can set to 4G shared mem??

Gordon

[Ravi_8]

Hi, Gordan

here is the info about the system which is running oracle9i and sybase.

# dmesg|grep -i phy
physical page size = 4096 bytes, logical page size = 4096 bytes
Physical: 1048576 Kbytes, lockable: 705268 Kbytes, available: 820344 Kbytes
# kmtune|grep shm
shmem 1
shmmax 4294967295
shmmni 1024
shmseg 1024

[Gordon_3]

Cool Ravi, this is the first time I know that shmax can set much higher than real physical, thx for info.