Estimating WAL usage during pg_basebackup

This is hard to tell, but You can get some estimation.
1. You can have WAL rate estimation from pg_xlog/ dir, i.e. How many WAL
generated per minutes
2. How long this pg_basebackup will last. Lets say for 3 hours.
Then You can multiple values in #1 and #2 to get rough estimation.

Hope this would help.

On Fri, Oct 31, 2014 at 1:52 AM, Mike Blackwell <mike.blackwell@rrd.com>
wrote:

I need to get an idea of how much WAL space will be required during a long
(many hours) pg_basebackup over a relatively slow network connection. This
is for a server that's not yet running PITR / streaming.

Any thoughts?
* <Mike.Blackwell@rrd.com>*

--
Regards,

Soni Maula Harriz

On Fri, Oct 31, 2014 at 2:52 AM, Mike Blackwell <mike.blackwell@rrd.com>
wrote:

I need to get an idea of how much WAL space will be required during a long
(many hours) pg_basebackup over a relatively slow network connection. This
is for a server that's not yet running PITR / streaming.

Any thoughts?

​You may want to explore
--xlog-method=method

This will enable you to 'fetch' wals at end of backup (which means you
should guess wal_keep_segment properly)​

Or you can 'stream' them which means WALs will be backed up in parallel.
This may introduce contention on network and hence may slow it down but you
will not have to guess wal_keep_segment​. See if this helps you.