Re: SHMBASE 0x44000000
>>-> -----Original Message-----
>>-> From: hariog@yahoo.com [mailto:hariog@yahoo.com]
>>-> Sent: Tuesday, September 06, 2005 7:52 AM
>>-> To: informix-list@iiug.org
>>-> Subject: SHMBASE 0x44000000
>>->
>>->
>>-> Hi All,
>>->
>>-> Redhat EL-AS3.0
>>-> Informix IDS 10.00.UC3
>>-> Physical Memory 8 GB
>>-> OLTP
>>->
>>-> One of our production server has got 3 instances (Live, Test and
>>-> Test2). I know its not a good option to have test/dev instances on
>>-> production server. You are right, eventually production server will
>>-> have only Live instance. Hoping !!!
>>->
>>-> My understanding about SHMBASE addressing is very poor. Sorry about
>>-> that.
>>->
>>-> I need to allocate SHMVIRTSIZE about 2.0 GB to Live instance
>>-> and 750 MB
>>-> each to Test and Test2. SHMTOTAL will be 0 for live and 1024000 for
>>-> Test and Test2.
>>->
>>-> Currently Live instance SHMVIRTSIZE is 900000 and SHMVIRTSIZE 300000
>>-> for other instances. SHMBASE for all three instances is 0x44000000.
>>-> onstat - shows 1338012 Kbytes for Live and 732596 Kbytes for Test and
>>-> Test2. Also /etc/syscntl has kernel.shmmax=1073741824
>>->
>>-> I need an advise on:
>>->
>>-> 1. SHMBASE 0x44000000 is ok for all three instances ? If not, what is
>>-> recommendation for Live, Test & Test2 SHMBASE ?
>>->
>>-> 2. What should be optimal value for kernel.shmmax as current
>>-> value will
>>-> surely insufficient for Live to start ?
>>->
>>-> Thanks in advance.
>>->
>>
>>
I just wondered whether anyone actually answered our questions ... note
that the below is specific to RHEL3 ...
1. SHMBASE advice.
Default SHMBASE is fine for all 3, and you will be able to get about 1.8
Gig allocated to an instance.
The layout of shared memory can be inspected by running the following
command where "pid" is the process id of the main CPU VP :
> cat /proc/"pid"/maps
If you have a look at that output you can see how the memory is laid out.
At a real push, you can move SHMBASE right down to :
SHMBASE 0xB000000L
and then you can allocate up to about 2.75 Gig in total.
2. kernel.shmmax value.
Set this to be 2 Gig - should be fine, even if the O/S splits a segment.
The starting value of 32 Mb for RHEL3 is pretty weak for IDS.
Thanks everyone for helping me out. Highly appreciated. Let me do some home work and then see how it goes.
Thanks everyone for helping me out. Highly appreciated. Let me do some home work and then see how it goes.