Re: page out

  • From: Stefan Moeding <dba@xxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 30 Mar 2010 18:10:59 +0200


Denis writes:

> Looks like it is from filesystem, what does that mean? Is it expected
> or not?

If it is the filesystem then it is kind of an expected behavior. You
probably don't use direct I/O for the database filesystems and what you
see is the I/O generated by the database to read and write blocks to and
from the buffer cache.

You could decide to enable direct I/O but you probably will have to
increase the buffer cache to compensate for the lost caching by the
operating system.

> What the meaning of "sr"?

Traditionally paging was an indication of memory shortage. Nowdays the
same mechanism is used to read blocks into the filesystem cache and so
the numbers also reflect normal I/O. The scan rate is an indication how
hard the operating system has to search for pages that can be freed. A
higher scan rate indicates a longer search for applicable pages and that
indicates memory shortage.


Other related posts: