Обсуждение: Move database

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
thewhole 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
thenew 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
theold VM, mount the NFS volume(s) on the new VM and start it there. 

It really depends on your system (storage) architecture.

Cheers,
Paul

On 11/10/20 7:48 AM, Yambu wrote:
> Hi
>
> What is the best way to move a database from one VM to another without 
> losing records from updating applications?
>
> regards

How much downtime can you suffer?
Are you staying at the same version, or upgrading, at the same?

-- 
Angular momentum makes the world go 'round.

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
thewhole 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
tothe 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)
onthe 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.

Hi

Same version of database, the old server will remain running with other databases, we just want to move one database.

regards

On Tue, Nov 10, 2020 at 4:16 PM Ron <ronljohnsonjr@gmail.com> wrote:

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.