[Orca-users] Where did the memory go....

[Dan Cushing]

Jon -

In Solaris 2.6 all unused memory is made available for I/O cache.  It
does not
return it to the "free" state when the I/O is completed.  A normal
expectation is
that the "free" memory number will drop gradually from boot up until it
is almost
zero and it will remain there.  As long as you are not seeing excessive
swapping
or paging, then things should be ok.

Look at the Available Swap graphs in ORCA.  That is a better indicator,
since
memory that is removed from the "free" pool for I/O caching still shows
as
available swap.  If you have 1 GB of disk swap space allocated and your
available
swap is reading 2 GB, then you still have 1 GB of memory that is
available for
program use (even though it doesn't show up in the free pool).

Solaris 8 doesn't behave this way.  Memory utilized only for I/O cache
shows up in
the free memory pool, which is much more intuitive.

Hope that helps.

Dan Cushing
NetIDEAS, Inc.



"Jon A. Tankersley" wrote:

> I've been trying to run down 'where did the memory go' on a 2.6 system.
> Free Memory is rapidly getting exhausted (about a Gig a day) and not
> coming back without a reboot.  When it is almost zero there is no
> appreciable paging or swapping.  We're suspecting FS cache (Lots of file
> I/O, logging of transactions, etc. on the system).  But I can't seem to
> find anything in the orcallator/percol file that shows a corresponding
> increase.
>
> SEToolkit/orcallator are running, apparently fine.
>
> Another thing I've noticed that one of the orca graphs is using the following:
> data                    pp_kernel
> data                    free_pages
> data                    pagestotl - pp_kernel - free_pages
> data                    pagestotl
>
> Why isn't it using pagesfree?  On the system I'm working with is showing
> pagesio of 0, and free_pages less than half of pagesfree....
>
> Is FS cache contained in pagesfree and not free_pages?  The free_pages
> agrees with sar -r data report on freemem pretty closely.
>
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