Re: SGA rules of thumb?
- From: kathy duret <katpopins21@xxxxxxxxx>
- To: don@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Tue, 8 May 2007 08:40:40 -0700 (PDT)
Check to see what is running when these ora-600 happen.
Check your snapshots this will tell you alot. Waits, what sql is running,
etc.
Very powerful and helpful. You may need to change then to run more often
capture more specific items.
What cronjobs, dbms_jobs are you running. Anything during these periods?
Is datapump going when you are doing RMAN backups?
I have found when datapump is going against large tables it grabs alot of
resources.
I had to revert back to using exports at one place because datapump used too
many resources when it was running even during the slowest part of the night.
Maybe you are doing a process in parallel that is grabbing all the resources.
I had some guy running a parallell 4 process on a single cpu test box and he
couldn't understand why the box was thrashing. This was to analyze tables,
when and how are you doing this? Setting to high a parallel on this can
cause issues.
Are you doing these large loads into the external tables at the time RMAN is
trying to back up. This could cause some issues.
Are you running RMAN through Veritas or another product to help you manage
backups?
I backup up to tape and my large Pool size is
Bottom Line: Look to see what is running when RMAN is or when these errors
are happening. Check the trace files to see if they shed any light. Search on
Metalink for the codes along with the Ora-600 and use the ora-600 utility to
see if that comes up with anything useful.
Good Luck
Kathy Duret
Been there and done that too many times...
Don Seiler <don@xxxxxxxxx> wrote:
Alright I'll make this scenario more specific. I'm an RMAN user. My
large_pool_size has been 16M "forever". The Backup & Recovery
Advanced Users Guide [1] says that:
"If LARGE_POOL_SIZE is set, then the database attempts to get memory
from the large pool. If this value is not large enough, then an error
is recorded in the alert log, the database does not try to get buffers
from the shared pool, and asynchronous I/O is not used."
and that the formula for setting LARGE_POOL_SIZE is as follows:
LARGE_POOL_SIZE = number_of_allocated_channels *
(16 MB + ( 4 * size_of_tape_buffer ) )
Of course I'm backing up to disk, not tape, but it would seem I should
be using a lot more than 16M. However, I don't see any errors in the
alert.log with "async" or "sync" in the text, so perhaps the large
pool is still just fine?
[1]
http://download-east.oracle.com/docs/cd/B19306_01/backup.102/b14191/rcmtunin003.htm#CACHJFED
On 5/7/07, Don Seiler wrote:
> I'm wondering if any of you have general "rules of thumb" when it
> comes to sizing the various pools and db buffer cache within the SGA.
> I'm going to go back to static SGA rather than risk ASMM thrashing
> about and causing another ORA-00600 at 2:30 in the morning. I can see
> where ASMM left the sizes at last, but just wondering what human
> thinks of things.
>
> This is Oracle 10.2.0.2 on RHEL3. sga_max_size is 1456M on 32-bit,
> going to be (at least) 8192M on 64-bit. The database is a hybrid of
> OLTP and warehouse. When I say "warehouse", I mean that large
> partitioned tables holding millions of records exist, and are bulk
> loaded via external tables and data pump throughout the day. Other
> than the bulk loading, those tables are read-only.
>
> Any advice would be appreciated (yes I've checked the V$*_ADVICE views as
> well).
--
Don Seiler
oracle blog: http://ora.seiler.us
ultimate: http://www.mufc.us
--
//www.freelists.org/webpage/oracle-l
---------------------------------
Ahhh...imagining that irresistible "new car" smell?
Check outnew cars at Yahoo! Autos.
Other related posts:
