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From: Greg Sabino Mullane <htamfids@gmail.com>
Date: Mon, 10 Nov 2025 10:33:20 -0500
Message-ID: <CAKAnmmKsgLmBOJQQouOFUHeEMjSCouK_dqx+xhdUNZ58UsUq3w@mail.gmail.com>
Subject: Re: Pgbackrest setup for two sites with limited bandwidth
To: Radu Radutiu <rradutiu@gmail.com>
Cc: pgsql-general <pgsql-general@postgresql.org>
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What you are asking for is tricky, but possible. You can setup two repos,
one for each server. On the first server (in datacenter A), you have a
"normal" pgbackrest configuration, with an explicit backup-standby=n. pg1-*
points to the local server, pg2-* points to the replica. The repo is in
datacenter A.Backups run from PG server in datacenter A, to the backrest
repo in datacenter A. WAL is archived from A -> A

On datacenter B, you have a separate local repo, a different stanza name,
and within that stanza, you have backup-standby=y, pg1 pointing to the
local pg, pg2 pointing back to A. In the postgresql.conf, your
archive-command pushes to this second repo, and archive_mode is "always".
Backups run from the PG server in datacenter A, but 99% of the files are
actually copied from the replica in datacenter B, and goes to the backrest
server in datacenter B. WAL is archived from B -> B.

That's the basic idea. It falls apart rapidly if this second data center
ever fails over.
Cheers,
Greg

--
Crunchy Data - https://www.crunchydata.com
Enterprise Postgres Software Products & Tech Support

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<div dir=3D"ltr"><div dir=3D"ltr"><div>What you are asking for is tricky, b=
ut possible. You can setup two repos, one for each server. On the first ser=
ver (in datacenter A), you have a &quot;normal&quot; pgbackrest configurati=
on, with an explicit backup-standby=3Dn. pg1-* points to the local server, =
pg2-* points to the replica. The repo is in datacenter A.Backups run from P=
G server in datacenter A, to the backrest repo in datacenter A. WAL is arch=
ived=C2=A0from A -&gt; A</div><div><br></div><div>On datacenter B, you have=
 a separate=C2=A0local repo, a different stanza name, and within that stanz=
a, you have backup-standby=3Dy, pg1 pointing to the local pg, pg2 pointing =
back to A. In the postgresql.conf, your archive-command pushes to this seco=
nd repo, and archive_mode is &quot;always&quot;. Backups run=C2=A0from the =
PG server in datacenter A, but 99% of the files are actually=C2=A0copied fr=
om the replica in datacenter B, and goes to the backrest server in datacent=
er B. WAL is archived from B -&gt; B.</div><div><br></div><div>That&#39;s t=
he basic idea. It falls apart rapidly if this second data center ever fails=
 over.</div><div>Cheers,</div></div><div dir=3D"ltr" class=3D"gmail_signatu=
re"><div dir=3D"ltr"><div>Greg</div><div><br></div><div>--</div><div>Crunch=
y Data - <a href=3D"https://www.crunchydata.com" target=3D"_blank">https://=
www.crunchydata.com</a></div><div>Enterprise Postgres Software Products &am=
p; Tech Support</div><div><br></div></div></div></div>

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