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Issue with SHMALL parameter
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* Issue with SHMALL parameter
@ 2012-09-18 13:59  data tanger <[email protected]>
  0 siblings, 1 reply; 3+ messages in thread

From: data tanger @ 2012-09-18 13:59 UTC (permalink / raw)
  To: pgsql-docs


Hi,
I'm using postgresql 9.1 as my database server on a linux server that has 8 GB of RAM.
After I changed the shared_buffers parameter to 2GB, I get the following error when I try to start postgres:
FATAL:  could not create shared memory segment: Cannot allocate memoryDETAIL:  Failed system call was shmget(key=5432001, size=2221539328, 03600).
Here are the shmall and the shmax params of my server:
#cat /proc/sys/kernel/shmmax     68719476736
#cat /proc/sys/kernel/shmall     4294967296
So as you see, shmall is greater than the requested size by postgres. Anyone have and idea?
thank you 		 	   		  

^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: Issue with SHMALL parameter
@ 2012-09-18 16:07  Tom Lane <[email protected]>
  parent: data tanger <[email protected]>
  0 siblings, 1 reply; 3+ messages in thread

From: Tom Lane @ 2012-09-18 16:07 UTC (permalink / raw)
  To: data tanger <[email protected]>; +Cc: pgsql-docs

data tanger <[email protected]> writes:
> Here are the shmall and the shmax params of my server:
> #cat /proc/sys/kernel/shmmax     68719476736
> #cat /proc/sys/kernel/shmall     4294967296

SHMALL is measured in pages not bytes on Linux.  I wonder if that value
is too large and is causing an internal integer overflow in the kernel.

			regards, tom lane




^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: Issue with SHMALL parameter
@ 2012-09-18 18:07  data tanger <[email protected]>
  parent: Tom Lane <[email protected]>
  0 siblings, 0 replies; 3+ messages in thread

From: data tanger @ 2012-09-18 18:07 UTC (permalink / raw)
  To: [email protected]; +Cc: pgsql-docs


Thank you for your answer. I think the value of shmall I have is very common cause I've seen it many times in other servers.Do you think there maybe a link between the request size of postgres and the swap size?
Here is the output of free -m
free -m             total       used       free     shared    buffers     cachedMem:          7867       1860       6007          0          5        595-/+ buffers/cache:       1258       6609Swap:         1023          2       1021
Regards,
> From: [email protected]
> To: [email protected]
> CC: [email protected]
> Subject: Re: [DOCS] Issue with SHMALL parameter
> Date: Tue, 18 Sep 2012 12:07:46 -0400
> 
> data tanger <[email protected]> writes:
> > Here are the shmall and the shmax params of my server:
> > #cat /proc/sys/kernel/shmmax     68719476736
> > #cat /proc/sys/kernel/shmall     4294967296
> 
> SHMALL is measured in pages not bytes on Linux.  I wonder if that value
> is too large and is causing an internal integer overflow in the kernel.
> 
> 			regards, tom lane
 		 	   		  

^ permalink  raw  reply  [nested|flat] 3+ messages in thread

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Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
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2012-09-18 13:59 Issue with SHMALL parameter data tanger <[email protected]>
2012-09-18 16:07 ` Tom Lane <[email protected]>
2012-09-18 18:07   ` data tanger <[email protected]>

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