Interesting script - thx for pointing it out.
SQL> @ash_wait_chains.sql "program2||program2" "event='log file sync'"
"to_date('05.10.2019 09:56:00','dd.mm.yyyy hh24:mi:ss')" "to_date('05.10.2019
09:57:30','dd.mm.yyyy hh24:mi:ss')"
%This SECONDS AAS
------ ------------------ ------------------
WAIT_CHAIN
------------------------------------------------------------------------------------------------------------------------------------
FIRST_SEEN LAST_SEEN
------------------- -------------------
100% 298 3.3
-> (JDBC Thin Client) (JDBC Thin Client) -> (LGWR) (LGWR)
2019-10-05 09:56:32 2019-10-05 09:57:02
Regards,
Dave
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> On Behalf
Of Noveljic Nenad
Sent: Monday, October 7, 2019 10:33 AM
To: 'oracle-l@xxxxxxxxxxxxx' <oracle-l@xxxxxxxxxxxxx>
Subject: RE: LGWR, EMC or app cursors?
CAUTION: This email originated from outside of D&B. Please do not click links
or open attachments unless you recognize the sender and know the content is
safe.
The event filter would be even better - to narrow down the output only for the
affected sessions:
@ash_wait_chains.sql program2||program2 "event='log file sync'"
"to_date('07.10.2019 08:15:21','dd.mm.yyyy hh24:mi:ss')" "to_date('07.10.2019
08:15:34','dd.mm.yyyy hh24:mi:ss')"
From: Noveljic Nenad
Sent: Montag, 7. Oktober 2019 17:27
To: 'dmarc-noreply@xxxxxxxxxxxxx' <dmarc-noreply@xxxxxxxxxxxxx>;
'oracle-l@xxxxxxxxxxxxx' <oracle-l@xxxxxxxxxxxxx>
Subject: RE: LGWR, EMC or app cursors?
* Is LGWR waiting on user sessions and user sessions are waiting on LGWR
and all that causes the disk to be 100%? Can I enable some sort of tracing on
LGWR and would that point to exactly what he's waiting on to prove where the
problem is?
Could you post the output of
https://github.com/tanelpoder/tpt-oracle/blob/master/ash/ash_wait_chains.sql<https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftanelpoder%2Ftpt-oracle%2Fblob%2Fmaster%2Fash%2Fash_wait_chains.sql&data=02%7C01%7Cherringd%40dnb.com%7C22f8365305dd4a71669b08d74b3bc2b6%7C19e2b708bf12437597198dec42771b3e%7C0%7C0%7C637060592356504647&sdata=%2FuuvEHnQrgalLpucxo9DR1EYxcUq2THMsXRoIL%2FibT8%3D&reserved=0>
for the observed time period to identify what's the root blocker doing?
@ash_wait_chains.sql program2||event2 1=1 "to_date('07.10.2019
08:15:21','dd.mm.yyyy hh24:mi:ss')" "to_date('07.10.2019 08:15:34','dd.mm.yyyy
hh24:mi:ss')"
Best regards,
Nenad
https://nenadnoveljic.com/blog/<https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnenadnoveljic.com%2Fblog%2F&data=02%7C01%7Cherringd%40dnb.com%7C22f8365305dd4a71669b08d74b3bc2b6%7C19e2b708bf12437597198dec42771b3e%7C0%7C0%7C637060592356514636&sdata=MzhLf6x2ypXbrc3t1qO2trr4HQFgk%2FTAjAFvMfdhOrc%3D&reserved=0>
From: oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>
<oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>> On Behalf
Of Herring, David
Sent: Montag, 7. Oktober 2019 17:18
To: 'oracle-l@xxxxxxxxxxxxx'
<oracle-l@xxxxxxxxxxxxx<mailto:oracle-l@xxxxxxxxxxxxx>>
Subject: LGWR, EMC or app cursors?
Folks, I've got a bit of a mystery with a particular db where we're getting a
periodic 25-30 pause between user sessions and LGWR processes and can't clearly
identify what's the cause.
* The database is 11.2.0.4, RHEL 7.5, running ASM on EMC.
* Sometimes once a day, sometimes more (never more than 5) times a day we
see user processes start waiting on "log file sync". LGWR is waiting on "log
file parallel write".
* At the same time one of the emcpower* devices shows 100% busy and service
time 200+ (from iostat via osw). mpstat shows 1 CPU at 100% on iowait. It's
not always the same disk (emcpowere1, a1, h1, ...), not always the same CPU.
EMC and sysadmins have confirmed there are no disk errors and from their
standpoint the disks are waiting on Oracle.
* During this time LGWR stats in ASH are all 0 - TIME_WAITED, DELTA*
columns. Only after the problem goes away (about 25 secs) these columns are
populated again, obviously the DELTA* columns 1 row later. LGWR's session
state is WAITING so I assume the column value observations are due to LGWR
waiting, as it won't write stats until it can do something.
I am stuck trying to find out, really prove who is the culprit or what exactly
the wait is on. Is LGWR waiting on user sessions and user sessions are waiting
on LGWR and all that causes the disk to be 100%? Can I enable some sort of
tracing on LGWR and would that point to exactly what he's waiting on to prove
where the problem is?
Regards,
Dave
____________________________________________________
Please consider the environment before printing this e-mail.
Bitte denken Sie an die Umwelt, bevor Sie dieses E-Mail drucken.
Important Notice
This message is intended only for the individual named. It may contain
confidential or privileged information. If you are not the named addressee you
should in particular not disseminate, distribute, modify or copy this e-mail.
Please notify the sender immediately by e-mail, if you have received this
message by mistake and delete it from your system.
Without prejudice to any contractual agreements between you and us which shall
prevail in any case, we take it as your authorization to correspond with you by
e-mail if you send us messages by e-mail. However, we reserve the right not to
execute orders and instructions transmitted by e-mail at any time and without
further explanation.
E-mail transmission may not be secure or error-free as information could be
intercepted, corrupted, lost, destroyed, arrive late or incomplete. Also
processing of incoming e-mails cannot be guaranteed. All liability of Vontobel
Holding Ltd. and any of its affiliates (hereinafter collectively referred to as
"Vontobel Group") for any damages resulting from e-mail use is excluded. You
are advised that urgent and time sensitive messages should not be sent by
e-mail and if verification is required please request a printed version.
Please note that all e-mail communications to and from the Vontobel Group are
subject to electronic storage and review by Vontobel Group. Unless stated to
the contrary and without prejudice to any contractual agreements between you
and Vontobel Group which shall prevail in any case, e-mail-communication is for
informational purposes only and is not intended as an offer or solicitation for
the purchase or sale of any financial instrument or as an official confirmation
of any transaction.
The legal basis for the processing of your personal data is the legitimate
interest to develop a commercial relationship with you, as well as your consent
to forward you commercial communications. You can exercise, at any time and
under the terms established under current regulation, your rights. If you
prefer not to receive any further communications, please contact your client
relationship manager if you are a client of Vontobel Group or notify the
sender. Please note for an exact reference to the affected group entity the
corporate e-mail signature. For further information about data privacy at
Vontobel Group please consult
www.vontobel.com<https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.vontobel.com&data=02%7C01%7Cherringd%40dnb.com%7C22f8365305dd4a71669b08d74b3bc2b6%7C19e2b708bf12437597198dec42771b3e%7C0%7C0%7C637060592356514636&sdata=Ec%2B6esfxg9XLGleemMFv4tc7jIMG3O9wUC4xVq2QoUE%3D&reserved=0>.