Subject: Re: Move database
To: pgsql-admin@lists.postgresql.org
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From: Ron <ronljohnsonjr@gmail.com>
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Date: Tue, 10 Nov 2020 08:16:43 -0600
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On 11/10/20 8:11 AM, Paul Förster wrote:
> Hi Yambu,
>
>> On 10. Nov, 2020, at 14:48, Yambu <hyambu@gmail.com> wrote:
>> What is the best way to move a database from one VM to another without losing records from updating applications?
> I assume you want to minimize down time? If so, set up a streaming replication on the new VM and let PostgreSQL copy the whole database over by itself as a standby database. After copying is finished and both databases are completely in sync, then shut down the old (primary) database and promote the standby database. After that, you can delete the old database.
>
> Assuming you can afford the down time, there is always the option of shutting the database down and scp or rsync it to the new VM and start it there.
>
> If you run it on some external storage like mounted NFS filesystems, you can shut it down, umount the NFS volume(s) on the old VM, mount the NFS volume(s) on the new VM and start it there.
>
> It really depends on your system (storage) architecture.

Given this set of circumstances, they could dismount the LUNs from VM-old, 
and mount them on VM-new:
* it's on a SAN,
* they're keeping the same version number,
* the database files are on dedicated mount points.

-- 
Angular momentum makes the world go 'round.