RE: Solaris 10 and Oracle 10g - swap space problem
- From: "Crisler, Jon" <Jon.Crisler@xxxxxxx>
- To: "Don Seiler" <don@xxxxxxxxx>, <mathias.magnusson@xxxxxxxxx>
- Date: Wed, 29 Jul 2009 10:42:46 -0400
Yes, I do have sga_max_size set.
-----Original Message-----
From: Don Seiler [mailto:don@xxxxxxxxx]
Sent: Wednesday, July 29, 2009 7:54 AM
To: mathias.magnusson@xxxxxxxxx
Cc: Crisler, Jon; oracle-l@xxxxxxxxxxxxx
Subject: Re: Solaris 10 and Oracle 10g - swap space problem
IIRC, lock_sga isn't valid in Solaris.
Jon, do you have sga_max_size explicitly set? I seem to recall this
behavior on Solaris 10 when sga_max_size was set explicitly. It
caused us much grief if we set sga_max_size to more than half of the
total physical memory on the box.
Don.
On Wed, Jul 29, 2009 at 1:42 AM, Mathias
Magnusson<mathias.magnusson@xxxxxxxxx> wrote:
> It makes the reservation, but if you have memory it would not use it. You
> just end up wasting some disk for swap you'll never use. If you increase
> Swap above 64 GB, does it work? Why would it crawl now? Fail for some DBs,
> but if you never use Swap, then allocation of it should not impact
> performance. Look at memory pressure to make sure the server never does
> pagescans - sr column i vmstat - of any real magnutude (over 200 is probably
> not desireable in production).
> Also, would the parameter lock_sga have any effect in Solaris? I've never
> tested it, but in theory it would pin SGA in real memory and never let it go
> to Swap, which also would mean that it should not reserve it. It's one of
> those parameter I've meant to play with, but I've never gotten around to
> actually test the effect.
> Mathias
>
> On Wed, Jul 29, 2009 at 1:31 AM, Crisler, Jon <Jon.Crisler@xxxxxxx> wrote:
>>
>> On Solaris 10, when I start my databases, I see my swap space usage
>> increase in a one for one ratio with memory utilization. System has 64gb
>> of memory. If I start up a 4gb database, I see 4gb of real memory used and
>> 4gb of swap space used up as well (as shown by top, swap -l, swap -s
>> etc.). This is purely a Oracle database server, and /etc/system and
>> projects / resource controls seem to be set up, so I do not understand why
>> swap is being touched. If I stop all oracle processes, swap drops down to
>> about 100 Mb used.
>>
>>
>>
>> I have taken great pains to make sure that NO swap is being used, yet any
>> little allocation of Oracle gets tossed into swap. I don't know where to
>> look after this- I would have suspected /etc/system or resource control /
>> projects to be at fault, or /etc/security (ulimits) but everything looks
>> ok. The system has 64g real, and about 54 gb swap- if I get close to
>> 54gb memory allocated oracle will return out of memory errors.. Needless to
>> say the system crawls.
>>
>>
>>
>> What am I overlooking ? TOP and swap -s / swap -l agree so its not a TOP
>> anomaly
>>
>>
>>
>> Example from TOP - I have 20g free, so why so much used in swap ?
>>
>>
>>
>> load averages: 0.64, 0.57,
>> 0.46
>> 00:26:34
>>
>> 1073 processes:1071 sleeping, 2 on cpu
>>
>> CPU states: 98.3% idle, 1.2% user, 0.5% kernel, 0.0% iowait, 0.0% swap
>>
>> Memory: 64G real, 20G free, 40G swap in use, 17G swap free
>>
>>
>>
>> PID USERNAME LWP PRI NICE SIZE RES STATE TIME CPU COMMAND
>>
>> 1997 oracle 1 39 0 4376K 2592K cpu/50 0:02 0.04% top
>>
>> 3454 oracle 1 52 0 16G 16G cpu/32 0:00 0.03% oracle
>>
>> 3456 oracle 1 24 0 16G 16G sleep 0:00 0.03% oracle
>>
>> 18589 oracle 1 59 0 16G 16G sleep 0:13 0.02% oracle
>>
>>
>>
>> Swap -s
>>
>> total: 39170184k bytes allocated + 2262264k reserved = 41432448k used,
>> 18017608k available
>
--
Don Seiler
http://seilerwerks.wordpress.com
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