Parity On Backup Unraid Server

[CodeEngie]

My main Unraid server runs 24/7, has parity, backs up to the cloud and backup Unraid server. The backup Unraid server is turned on once a week for backups and I was wondering if it makes sense to have parity on the backup Unraid server? Thank you.

[trurl]

Is it going to be easy to recover the data on a failed disk by just running another backup, or would it be easier to recover a failed disk from parity?

[CodeEngie]

I guess it can go both ways but I feel the backup would be faster.

[trurl]

Have you ever rebuilt a disk from parity? It is very easy, speed will depend on size.

[CodeEngie]

I have. I did it when I upgraded my 8TB drives to 16TB.

[Michael_P]

2 hours ago, CodeEngie said:

if it makes sense

 

That's subjective in relation to your personal situation and needs - if you have an extra drive, and no need for it in your main server, then You Might As Well™️use it. You can always remove it later if you need it somewhere else.

[ConnerVT]

Obviously, you must have a 3-2-1 backup plan for all of the data on the backup server.  😝

 

I don't run a parity drive on my backup server.  While it is nice to have a way to rebuild a lost drive from parity, there is a real cost of implementing parity as well:

• Write speed is much slower with parity.
• Extra drive could be used for additional data storage. 

[TimTheSettler]

I'm guessing that most of you have had the good fortune to never need to restore because it's a pain in the royal butt.  I've since learned to buy good reliable drives and all my servers have dual parity.  If money is a problem then I can understand but keep in mind that time is money.

[Michael_P]

5 hours ago, TimTheSettler said:

I'm guessing that most of you have had the good fortune to never need to restore

 

This discussion is about backup servers. Unless you're restoring backups of your backups to your backup server, I'm not sure what case you're trying to make.
 

Edited November 19, 2023 by Michael_P

[ConnerVT]

If a drive fails in my backup server, the restore process is:

- Replace drive in backup server.

- Run backup script from main server.

 

My butt feels pretty pain free.

[TimTheSettler]

On 11/19/2023 at 6:46 AM, Michael_P said:

This discussion is about backup servers. Unless you're restoring backups of your backups to your backup server, I'm not sure what case you're trying to make.

 

If a drive on your backup server dies then you need to restore the contents of that drive.  If it's a single drive then that's easy to do but if you have multiple drives in an array and the data is spread across the drives and then one drive fails then will you know what you've lost?  In this case you will need to back up all that data.  In my case that's a lot of data so I'd rather not waste time backing up 30TB of data.  Instead, I buy a new drive and let unRAID restore one 10TB drive in less than a day.

 

One last point is that my backup server uses snapshots so losing that server would suck.  I could restore the data from the source but I would lose the history.

 

I guess it just depends on how the backup server is set up.  My post above and here is simply meant as another perspective.

[Michael_P]

6 hours ago, TimTheSettler said:

will you know what you've lost?

 

Not to beat a dead horse, and I'm a firm believer of You Do You™️ , but the backup script/program will know and back up what's missing (snapshots aside) and back it up again - no need for a full backup. As I've said above, if you have the spares to have redundancy on your backup server, then you might as well use it.

[itimpi]

7 hours ago, TimTheSettler said:

In this case you will need to back up all that data.

If you use something like rsync to do this then you can set it to simply skip over files that are already there.

[ConnerVT]

19 hours ago, TimTheSettler said:

If it's a single drive then that's easy to do but if you have multiple drives in an array and the data is spread across the drives and then one drive fails then will you know what you've lost?

 

That is why I use rsync to back up.  It will do a quick inventory of what is the same, and what is missing.  Then only transfer that which is missing.  The backup server can eat data at 1Gb speed on a 2.5Gbe network (plenty of head room for everything else), the drives write at around 200MB/s with no parity to deal with.  My guess is that the data would be fully restored by copying it over faster than rebuilding the drive.