Irrelevant thoughts of an oracle DBA

27 November 2007

linux / unix kernel parameters follow-up

Filed under: infrastructure — Freek D'Hooge @ 21:21

This is a follow-up note on my prior linux / unix kernel parameters post

Yesterday I received some feedback from oracle about why the core dump has a 4 GB limit and why you should therefore limit the shmmax to a maximum of 4GB:

” Normally on x86_64 a coredump is not limited to 4 GB, but a coredump is affected in different levels: namely memory, I/O and disk.
Most of the limitations are due to the filesystem used.
If the coredump routine in the kernel is not using the right kernel calls or the filesystem cannot handle files bigger than 4 GB (like reiserfs or some old ext2),
then the coredump will be affected.

For this reason, setting shmmax < 4GB on x86_64 is more a recommendation.”

After reading this I, closed the service request…



  1. very interesting, but I don’t agree with you

    Comment by Idetrorce — 15 December 2007 @ 15:06 | Reply

  2. what are the kernel parameters in oracle dba installation ans total what its name

    Comment by kernel parameters — 8 March 2008 @ 15:25 | Reply

  3. ans total?

    Comment by dhoogfr — 9 March 2008 @ 10:32 | Reply

  4. Hi
    I had installed 10g XE, I have created a new user in th DB while importing the dump its gives the error
    can’t import more than 4GB.( Alredy data files are around 4GB).
    plz give any solution to resolve the problem.


    Comment by Muthu — 24 June 2008 @ 8:42 | Reply

  5. Muthu,

    The limit you are experiencing is not a memory limit, but a build in limitation of oracle XE.
    Oracle XE is a free version of the oracle database and therefore has been limited to a maximum of 4 GB in size.
    The only real option you have if you need more then 4GB of data is to upgrade to a full oracle version (I think the cheapest version would be oracle standard edition one).

    Check following links for more information about oracle express:

    Comment by dhoogfr — 24 June 2008 @ 8:51 | Reply

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