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Home -> Community -> Usenet -> c.d.o.server -> Re: Oracle Eats RAM, none left for Gods
A copy of this was sent to JoshNarins <joshnarins_at_my-dejanews.com>
(if that email address didn't require changing)
On Mon, 26 Apr 1999 21:33:11 GMT, you wrote:
>I come from a UNIX SA background on Digital, HP-UX, SCO and some older SunOS
>and Solaris. I had never heard of normal swap in use.
All processes allocate some swap space. On a machine with nothing but the OS running and lots of memory (2 gig in this case on solaris 2.6) we see:
$ swap -l
swapfile dev swaplo blocks free /dev/dsk/c0t1d0s1 32,9 16 4194272 4194272 /dev/dsk/c3t0d0s1 32,361 16 4194272 4194272
$ swap -s
total: 23616k bytes allocated + 5584k reserved = 29200k used, 5900488k available
so, with nothing going on, we have 23meg of swap consumed. Starting up the the database with a 122 meg SGA we see...
SVRMGR> connect internal
Connected.
SVRMGR> startup
ORACLE instance started.
Total System Global Area 122568080 bytes Fixed Size 64912 bytes Variable Size 55214080 bytes Database Buffers 67108864 bytes Redo Buffers 180224 bytesDatabase mounted.
$ swap -l
swapfile dev swaplo blocks free /dev/dsk/c0t1d0s1 32,9 16 4194272 4194272 /dev/dsk/c3t0d0s1 32,361 16 4194272 4194272
$ swap -s
total: 171776k bytes allocated + 9744k reserved = 181520k used, 5748008k
available
That I know have 177meg allocated -- but i'm not swapping, not at all. Swap is allocated to/by processes at startup for many reasons. Many Unix systems allocate 100% overhead -- SunOS4.x was one as I recall where you had to have more swap then real memory. With Solaris 2.x, you can use real ram as swap (and not even have any swap configured).
A couple of good articles on this:
http://www.sunworld.com/swol-07-1998/swol-07-perf.html
http://www.sunworld.com/sunworldonline/swol-12-1997/swol-12-insidesolaris.html http://www.sunworld.com/sunworldonline/swol-01-1998/swol-01-insidesolaris.html
>There is no swapping
>going on, but before we added the RAM there was occasionally a lot of paging.
>The short term expected memory shortfall also was high a lot.
>
I think you moved the swap allocations from disk to RAM by adding that memory.
>So, already, you have answered my question in stating that SOME SWAP is ok.
>
>> How big is your SGA? Each of the components of the SGA?
>> What else do you do on the machine?
>> How many connected users do you typically have? What are they typically
>doing?
>
>SGA is 1.3Gig. I wouldn't know about the components, sorry. I'm not even the
I would say that on the original 2gig machine, a 1.2 gig SGA is oversized. In fact, the 1.2 gig SGA may be way oversized for the database on a 3gig machine. The SGA should only be as large as you need it, not as big as we can make it. You might consider asking the DBAs to justify why they went this size. How big is the database itself? It may well be (or not) that the SGA is larger then needs be for this system.
>DBA, it is just a very important system and they spend time doing things I did
>not recognize as useful, meanwhile, memory usage was atrocious.
>We do NOTHING else on the machine. Except monitor it.
>Connected users ~140-200. Typically doing routine queries.
>
>No response is necessary, thank you for your time.
>
>-----------== Posted via Deja News, The Discussion Network ==----------
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Thomas Kyte
tkyte_at_us.oracle.com
Oracle Service Industries
Reston, VA USA
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