Hi Charlotte,
Have you got the logs for good vs bad backups? I’d start with that.
Are there new batch jobs competing for cpu time?
Although backup size may not have changed due to compression, perhaps the db
itself has grown and Rman has to scan more blocks before compression?
Compare the sizes:
Rman> report schema as at ‘sysdate - 14’;
Rman> report schema;
When looking at cloud backups a few years ago we eventually had to do tcpdumps
to see what the calls were doing and where they were going.
Has the region changed somehow? Maybe you’re connecting to Australia? 😆
Cheers,
Leng
On 6 Nov 2019, at 2:04 am, Jeffrey Beckstrom <jbeckstrom@xxxxxxxxx> wrote:
What does your internet traffic look like during this time period since you
are going to the Cloud?
Hi Mladen,"Charlotte Hammond" (Redacted sender"charlottejanehammond" for DMARC)
<dmarc-noreply@xxxxxxxxxxxxx> 11/5/19 9:48 AM >>>
These are SBT channels using Oracle Secure Backup Cloud Module (OSBWS).
No backup suite is being used - these are simply command line RMAN jobs run
from a scheduler.
I'll have a look at profiling the CPU usage a bit more and see where that
takes me. Unfortunately, as mentioned, I do not have a baseline available
for the "good" backups.
Thanks,
Charlotte
On Tuesday, November 5, 2019, 12:14:19 PM GMT, Mladen Gogala
<gogala.mladen@xxxxxxxxx> wrote:
Hi Charlotte!
What kind of a channel do you allocate, disk or SBT? If SBT, what kind of
backup suite are you using? Stuff like NetBackup, Commvault or TSM is highly
complex and dependent on may factors.
Regards
On 11/5/19 3:27 AM, Charlotte Hammond (Redacted sender charlottejanehammond
for DMARC) wrote:
Hi Nenad,
The average run queue is about 20 (peaking at about 25) whilst the backup is
running. The figure is the same for both the slow and fast runs. I've
graphed them out and they look pretty much the same. This is a fairly high
figure but it doesn't seem to have changed.
We have 16 backup channels and 16 CPUs (2 threads per processor).
Yes, the compression is "basic" but that has not changed.
Thanks,
Charlotte
On Monday, November 4, 2019, 09:26:33 PM GMT, Noveljic Nenad
<nenad.noveljic@xxxxxxxxxxxx> wrote:
Hi Charlotte,
Run queue length of 20-25 means the number of processes competing for CPU.
How many CPUs do you have? How many RMAN channels are configured?
What was the average length of run queues during a good run?
With regard to backup compression, basic will use significantly more CPU than
the others, but as you mentioned that the backup size is the same, the backup
algorithm probably hasn‘t changed.
I‘d therefore suggest first clarifying the CPU load on the server.
Best regards,
Nenad
Von: Charlotte Hammond <charlottejanehammond@xxxxxxxxx>
Datum Montag, 04. Nov. 2019, 6:15 PM
An: dmarc-noreply@xxxxxxxxxxxxx <dmarc-noreply@xxxxxxxxxxxxx>, ORACLE-L
<oracle-l@xxxxxxxxxxxxx>, Noveljic Nenad <nenad.noveljic@xxxxxxxxxxxx>
Betreff: Re: Sudden Backup Slowdown
Hi Nenad,
The only real difference between the AWR reports is that the statistic "RMAN
cpu time (backup/restore)" is about 50% longer than before. Sar shows the
run queues as 0 (or close to 0) before and after the backup in both cases and
similar during the backup (about 20-25).
Thanks,
Charlotte
On Monday, November 4, 2019, 02:51:38 PM GMT, Noveljic Nenad
<nenad.noveljic@xxxxxxxxxxxx> wrote:
If there weren’t any idle CPUs during backup, I’d first verify the statement
“The server itself has no other activity during the backup window.” by
measuring the length of the run queues. In other words, to confirm there
aren’t any other processes competing for CPUs.
What differences do you see in AWR reports?
Best regards,
Nenad
https://nenadnoveljic.com/blog/
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> On Behalf
Of Charlotte Hammond
Sent: Montag, 4. November 2019 15:22
To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
Subject: Sudden Backup Slowdown
Hello All,
I'm trying to explain why my level 0 rman backups have suddenly jumped from
8hours to 12 hours. The size of the backup has barely changed and there has
been no configuration changes. AWR and O/S statistics show that CPU for all
the channels are maxed out at ~99% (presumably backup compression) for most
of this time, both in the 8 hour case and 12 hour case. The server itself
has no other activity during the backup window.
This is on 11.2.0.4 on AWS EC2 backing up to S3 storage.
I'm not looking for tuning advise here (thanks though!) - I'm really hoping
for some advise on finding an explanation for the change in times. Given
that all it's doing is sitting on CPU I'm not sure what else I can
investigate - especially with limited ability to cross-reference it with the
"good old" runs. It's been 8 hours for months and months, and has now been
12 hours for the last 3 weeks. There was no gradual increase - just a step
change.
Thanks!
Charlotte
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--
Mladen Gogala
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Tel: (347) 321-1217