Consistency of multi-VM Snapshots

[aurelienc]

Hello!

I am considering moving towards a cluster of proxmox servers.
The idea is to have dedicated servers for:
- the web server & app server itself
- one for each DB servers (we use mysql & mongo)

Before doing so I would like to make sure:
Is there is a way to trigger snapshots simultaneously on several VM ensuring that they are in a consistent state (one compared to the other) and knowing that they are not physically on the same server?

I would need to make absolutely sure that mysql & mongo are as consistent as possible one with the other at their store data that is "connected" together by the web/app server.

I tried to find something already existing on the forum but let me know if I missed something!

Thanks!

Aurelien

 

[flow]

If i understand you correctly you would like to use 3 Proxmox servers with the first having 2 VMs (web &app) and the second and third node as a host for a DB server each?
The most consistent state you could achieve with the built-in backup, is to create backup jobs for each VM individually starting at exactly the same time.

Other than that you would have to script your own backup routine.

 

[Cyberco Ltd]

I think that maybe your looking in the wrong direction at this.

Both these databases support real time replication of data so a better approach would be to build secondary server containers on an alternative server and have these collect backups in real time - so you always have x2 copies of live data.

Then - if you want an exact point-in-time consistent backup - temporary shutdown your secondary mongo/mysql servers (note live system will continue to run) and back them up - then once backed up restart them and within a short time they will catch up with live once more.

This is a simplified technique to an automated system we are using with our in-house developed systems at Cyberco Ltd and it works very effectively.

Hope this helps

Mark.

Hello!

I am considering moving towards a cluster of proxmox servers.
The idea is to have dedicated servers for:
- the web server & app server itself
- one for each DB servers (we use mysql & mongo)

Before doing so I would like to make sure:
Is there is a way to trigger snapshots simultaneously on several VM ensuring that they are in a consistent state (one compared to the other) and knowing that they are not physically on the same server?

I would need to make absolutely sure that mysql & mongo are as consistent as possible one with the other at their store data that is "connected" together by the web/app server.

I tried to find something already existing on the forum but let me know if I missed something!

Thanks!

Aurelien

 

[aurelienc]

Hello flow, hello Mark,

Thanks a lot for your replies.
Reading your answers I indeed understand that I was definitely looking at this from a wrong perspective and that implementing this wrong perspective would have been a pain!

Thanks Mark for the solution proposed, I think I will follow this idea.

Aurelien

 

[Cyberco Ltd]

Hi Aurelien,

Your very welcome.

Once you begin down this path it will come together quite quickly - good luck.

Thanks,

Mark.

Hello flow, hello Mark,

Thanks a lot for your replies.
Reading your answers I indeed understand that I was definitely looking at this from a wrong perspective and that implementing this wrong perspective would have been a pain!

Thanks Mark for the solution proposed, I think I will follow this idea.

Aurelien