RE: ASH Buffer max size
Date: Sat, 18 Apr 2009 20:51:29 +0200
it seems that the upper limit of _ash_size is 250MB (on 10g and 11g). I have tested it on OEL5.3 with 10.2.0.4 and 18.104.22.168 (1CPU ;( only ) The parameter _ash_size is set as requested , but the real value of the buffer is limited to 250MB
SQL> select POOL , NAME , BYTES from V$SGASTAT where NAME='ASH buffers' ;
POOL NAME BYTES ------------ -------------------------- ---------- shared pool ASH buffers 266338304
This result is independent of Oracle shared memory management discipline (AMM or ASMM)
From: Martin Berger [mailto:martin.a.berger_at_gmail.com] Sent: Donnerstag, 16. April 2009 21:25
Subject: Re: ASH Buffer max size
a short google search brought some ambiguous informations:
it's controlled by _ash_size
one formula is
Max( Min ( No. of CPU * 2 M, 5% of SHARED_POOL_SIZE, 2% of SGA_TARGET) ,1M) -
another: max (min (#of CPUs * 2MB, 5% of SHARED_POOL_SIZE, 30MB), 1MB) -
both seem to be about 10g.
Currently I have no informations if there are any changes in 11g, sorry.
happy testing with _ash* parameters.
> Hallo Listers,
> I have s simple question:
> What is the maximum size if ASH buffers.
> Some documents say it is 30Mb, other documents say it is 128MB (for
> Is there any change in the upper ASH buffers size 11GR1 ?
> Many thanks in advance.
> Best Regards. Milen