Problem with large SGA

  • From: daniel.hubler@xxxxxxxxxx
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 7 Oct 2005 13:23:37 -0500

Oracle v8.1.7.4
OpenVMS 7.3-2

We recently increased the size of our SGA from 40gig to over  100gig by 
increasing our shared pool and block buffer cache.
Everything has gone very well.

One side effect we have encountered is that the time it takes to put all 
our tablespace into HOT backup
(ALTER TABLESPACE xxxxx BEGIN BACKUP;)
has gone from 1 hour  to  about 3.5 hours.
In retrospect, this makes some sense as the buffer cache is examined for 
blocks from the specific
tablespace to be written to disk;  more cache to examine so it takes more 
time.

Oracle has confirmed this.  We have received the "expected behavior" 
answer regarding this issue.

Anybody have any ideas on how to minimize the impact of this?






Dan Hubler
Database Administrator
Aurora Healthcare
daniel.hubler@xxxxxxxxxx

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