Re: rman backup slow even after patching it

From: Moustafa Ahmed <moustafa_dba_at_hotmail.com>
Date: Mon, 15 Aug 2022 19:13:48 +0000
Message-ID: <PH7PR22MB3637570E2C2C004E682D64C7E1689_at_PH7PR22MB3637.namprd22.prod.outlook.com>

Try
Alter session set optimizer_mode=RULE;

Insider man run block…

Also what is the most significant wait event? Is it compute obsolete files?

On Aug 15, 2022, at 1:37 PM, Beckstrom, Jeffrey <jbeckstrom_at_gcrta.org> wrote:


In 19.14, rman backup significantly slower than in 11g. This morning I put on some RMAN patches to no effect. In the rman trace file from a running backup I see:

Adjusting buffer count to honor available PGA; old bufcnt: 4, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 4, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 5, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 6, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 4, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 5, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 8, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0
Adjusting buffer count to honor available PGA; old bufcnt: 16, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 892876434, pga_available: 0

Backup envisage an unusual situation due to PGA memory availability: we are using only 2 read threads (instead of 9) for the current backup session Adjusting buffer count to honor available PGA; old bufcnt: 4, new bufcnt: 2, pga_agg_limit: 0, pga_agg_target: 0, pga_agg_used: 913692181, pga_available: 0

Pga_aggregate targe is set at the cdb to a value. At the pdb level it is 0. Pga_aggregate_limit is not set anywhere.

Do I need to set the pga_aggregate limit?

Do I need to set both parameters at the PDB level?

Jeffrey Beckstrom
Greater Cleveland Regional Transit Authority 1240 W. 6th Street
Cleveland, Ohio 44113

--
http://www.freelists.org/webpage/oracle-l

Received on Mon Aug 15 2022 - 21:13:48 CEST