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rman performance
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Message Score Author Date
Hi, I have a backup stored on a zfs storage con...... Alain Bourgeois Jun 18, 2020, 15:07
Well... no. For modern versions, even with BIGF...... Jan Schnackenberg Jun 18, 2020, 16:23
I restore and recover using oracle 12.2. Any sett...... Alain Bourgeois Jun 18, 2020, 16:40
In that case: read up on the "SECTION SIZE" parame...... Jan Schnackenberg Jun 18, 2020, 16:48

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Subject: rman performance
Author: Alain Bourgeois, Belgium
Date: Jun 18, 2020, 15:07, 50 days ago
Os info: linux 6
Oracle info: 12.2
Message: Hi,

I have a backup stored on a zfs storage connected through a 10Gbps link.
Reading using a block size of 8Kb gives 40Mb/sec, block of 800Kb gives 1.8Gbps.

[root ~]# dd if=/backup_db/tmp.tmp of=/dev/null bs=8096 count=1000000
1000000+0 enregistrements lus
1000000+0 enregistrements écrits
8096000000 octets (8,1 GB) copiés, 204,269 s, 39,6 MB/s
[root ~]# dd if=/backup_db/tmp.tmp of=/dev/null bs=809600 count=10000
10000+0 enregistrements lus
10000+0 enregistrements écrits
8096000000 octets (8,1 GB) copiés, 4,4225 s, 1,8 GB/s

Speed difference is huge according to block size used.

Aside parallelism (x channels), is there any setting in rman that can be used to speed up reading the backup from storage during restore/recovery?
Same question to speed up writes to ASM during restore?

( I restored last week a backup at 28Mb/sec, very slow).

Thanks.
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Subject: Re: rman performance
Author: Jan Schnackenberg, Germany
Date: Jun 18, 2020, 16:23, 50 days ago
Message: Well... no.

For modern versions, even with BIGFILE tablespaces, you could backup your tablespace with a high number of parallel workers. And restore, too, of course.

But in 11gR2 that wasn't possible, yet, and since the backup wasn't using this feature, the restore cannot use it, either.

I'm not aware of any options to speed this up.

Writing to ASM is more or less the same issue.

Regards,
Jan
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Subject: Re: rman performance
Author: Alain Bourgeois, Belgium
Date: Jun 18, 2020, 16:40, 50 days ago
Message: I restore and recover using oracle 12.2.
Any setting at that point?
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Subject: Re: rman performance
Author: Jan Schnackenberg, Germany
Date: Jun 18, 2020, 16:48, 50 days ago
Message: In that case: read up on the "SECTION SIZE" parameter to the BACKUP command: https://docs.oracle.com/database/121/RCMRF/rcmsynta006.htm#RCMRF107

This, combined with multiple Channels, can significantly boost your speed. Unfortunately, no guarantees, whatsoever.
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