Re: pg_basebackup inconsistent performance

On 5/6/20 5:44 AM, Jasen Lentz wrote:
> We have pg_basebackup running on two of our DB servers that are 
> replicated.  We are running postgres 11, and it seems we are getting 
> inconsistent performance from the backups and unsure as of why.  We 
> start out at 5-6 hours over a dedicated 10G port for 7TB.  It creeps up 
> to 8-9 hours then all of a sudden takes 12-16 hours.  There seems to be 

I'm guessing the above happens from one run to another correct?

Where are the machines you are backing up from/to relative to each on 
the network?

Is there increased activity on the database servers e.g. inserts, 
updates, etc during the extended backups?

> no rhyme or reason for the extended backup times.  The command we use 
> for backups is as follows:
> 
> On server 2 (secondary), starts at 4PM
> 
> pg_basebackup --pgdata=/opt/postgres/pgbackup/`echo $DATE` 
> --format=plain --write-recovery-conf --no-sync --wal-method=stream 
> --checkpoint=fast --label=`hostname`-`echo $DATE` --no-verify-checksums 
> --host=<server1> --username=replication --port=5432
> 
> On server 1 (Primary), starts at Midnight
> 
> pg_basebackup --pgdata=/opt/postgres/pgbackup/`echo $DATE` 
> --format=plain --write-recovery-conf --no-sync --wal-method=stream 
> --checkpoint=fast --label=`hostname`-`echo $DATE` --no-verify-checksums 
> --host=<server2> --username=replication --port=5432
> 
> I’m not sure why or how we are running into the weeds.  I am the 
> SysAdmin and am not familiar with the inner workings of the DB.  I can 
> pass any commands that need run along to our DBA.
> 
>  From the OS perspective, we are not seeing any problems with CPU, 
> memory or disk.  We are running on RHEL 7.7
> 
> Thanks!
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com