Any chance this db is on AIX?
Herr Upgrade reminded me that there's a known bug for 12.1-12.2 upgrades that
exhibit this behavior...could be it crept into 18c.
-----Original Message-----
From: Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
Sent: Saturday, May 18, 2019 5:29 AM
To: oracle-l@xxxxxxxxxxxxx; ttrnguyen@xxxxxxxxx
Subject: Re: Memory needed for upgrade to 18c
What are you doing to check the memory usage of each instance ? Is this just
the shared memory or are you doing something to include the actual memory usage
of all the processes attached to the SGA as well ? Is the increase apparent
from Oracle's perspective or is there something about Oracle's use of memory
which has changed the way it's O/S memory pages that has led to more memory
being allocated for the O/S memory map ? (Possible clues in the alert log if
you've got old and new.)
You say 2GB more per instance - how much memory was each instance using before
the upgrade (to give us some idea of the percentage increase).
Do you have any record of memory allocation on startup for the databases you've
upgraded - it's almost always the case that Oracle Corp. finds some new
"overhead" to stuff into the code as you upgrade. 18c has
You say you have 22 single instances on that machine - are they all running
separate virtual machines (please translate to AIX-equivalent terminology) or
do you have many virtual machines with one (or more) instances per machine.
(And can you tell us something about the total CPU count and memory of the
hardware).
You say that the parameters are the same - but are you comparing all the
parameters that you DIDN'T set that may have changed their default values.
Again a comparison of old and new alert logs may help. As a quick check for
large scale changes you could compare the before and after results of
select pool, sum(bytes) from v$sgastat group by pool order by 1;
This MIGHT highlight a significant change.
Regards
Jonathan Lewis
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> on behalf
of Thanh NGUYEN <ttrnguyen@xxxxxxxxx>
Sent: 18 May 2019 08:17:52
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Memory needed for upgrade to 18c
Hello Stefan,
Thank you very much for your answer.
1) We did not change any parameter related to memory. Furthermore, we got the
same issue (memory usage increased), 2 years ago, when we upgraded from
11.2.0.4 to 12.1.0.2.
2) We have 22 single instances at that server. It will take time if we
determine the the consumption of each process.
Do you have any simpler idea?
Best regards,
Thanh NGUYEN
------------------------
$ ps -ef|wc
3423 30419 238850
8:58:13 z004969:/users/ucib/z004969
$ ps -ef|grep smon|grep -v grep|wc
22 198 1498
On 5/17/19 9:42 AM, Stefan Koehler wrote:
Hello Thanh,
ah AIX and Oracle is like Tom and Jerry ;-)
Maybe the good old "USLA heap" problem is back again. However if you have not
changed any parameter (e.g. SGA_TARGET, MEMORY_TARGET, PGA_AGGREGATE_TARGET)
and you are not using more (over-allocated) PGA than before than it is very
likely caused by heap memory consumption of each Oracle process - you can check
the memory and break it down with "svmon" very easily (
https://urldefense.proofpoint.com/v2/url?u=http-3A__www-2D01.ibm.com_support_docview.wss-3Fuid-3Disg3T1012834&d=DwIFAw&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=N2hWu5HFsaIjmMkjQbnlokJ7uinNZMgPVk8rqPT9esM&m=w2YYDprae2S8mohFPbLgipsKVm_Z-0dMIWQWM4DJyP8&s=InsscDvOzj9BnLgT0dxf4BQTnBBXDFU705LQfTO9pMU&e=
).
Best Regards
Stefan Koehler
Independent Oracle performance consultant and researcher
Website:
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.soocs.de&d=DwIFAw&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=N2hWu5HFsaIjmMkjQbnlokJ7uinNZMgPVk8rqPT9esM&m=w2YYDprae2S8mohFPbLgipsKVm_Z-0dMIWQWM4DJyP8&s=63xTLyuvJv3h2GeetG08mAbbNEWCwSDMo4oggme6qEU&e=
Twitter: @OracleSK
Thanh NGUYEN <ttrnguyen@xxxxxxxxx><mailto:ttrnguyen@xxxxxxxxx> hat am 16. Mai
2019 um 21:31 geschrieben:
Hello,
Aix 7.2 ML03
We upgraded 5 instances from 12.1.0.2 to 18c, without changing any parameter.
Then we observed that memory is used more than before the upgrade, nearly 2GB
more for each.
Do you have any experience/explanation about that please?
Thank you in advance.
Best regards,
Thanh NGUYEN
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