What would you do?

[Spewu]

Hi there

 

I have a server with 3 disks + a cache disk:

Parity: 8TB

Disk 1: 2TB

Disk 2 8TB

 

I am currently using 6.29TB in total.

 

I just bought a new 8TB disk, because I thought Disk 2 failed. It turned out it has not failed, so now I have an extra 8TB disk. I am wondering how best to proceed from here, so I would like to hear some opinions from the more experienced people here.

 

I am thinking I have these options:

 

1. Keep the new 8TB disk in its wrapping, so I have a spare disk available quickly when the next disk fails

2. Replace the 2TB disk with the new 8TB disk, to increase the total size of the array

3. Replace the 2TB disk with the 8TB disk, but use the new 8TB disk as a second parity disk

 

(I only have 3 HDD cages in my server)

 

I don't have any immediate plans of needing more storage on the array, so I am currently leaning towards option 3 - to improve the resiliency of the data. My thinking is that I can always recommission the second parity drive as a data drive in case my storage needs increase in the future.

 

What would you do?

[JonathanM]

Option 4. Use the new disk as a periodic full backup of your data.

 

RAID, Unraid, etc, are for high availability, where you still have access to your data uninterrupted while replacing a failed drive. That is the ONLY data protection they offer in this context.

 

Drive failure is only one of many ways to lose data. Accidental or malicious deletion, user error, file system corruption, etc, are not protected against, only backup can help there. So, to improve your data resiliency, you need a full versioned backup in a different physical location.

[Spewu]

6 minutes ago, jonathanm said:

Option 4. Use the new disk as a periodic full backup of your data.

 

RAID, Unraid, etc, are for high availability, where you still have access to your data uninterrupted while replacing a failed drive. That is the ONLY data protection they offer in this context.

 

Drive failure is only one of many ways to lose data. Accidental or malicious deletion, user error, file system corruption, etc, are not protected against, only backup can help there. So, to improve your data resiliency, you need a full versioned backup in a different physical location.

That is also a good idea - thanks!

I do have a script that is backing up my most important data to Azure Cold Storage on a weekly schedule, so I feel somewhat safe in that regards for the time being. But I will definitely consider your suggestion.

[itimpi]

I don’t see how option 3 is possible as you only have 3 slots

 

Option #2 looks possible and the old 2TB disk could then perhaps be plugged into an external USB box to give you space to be used for backups, or other uses?

[Spewu]

26 minutes ago, itimpi said:

I don’t see how option 3 is possible as you only have 3 slots

 

Option #2 looks possible and the old 2TB disk could then perhaps be plugged into an external USB box to give you space to be used for backups, or other uses?

I think option 3 is possible because I only use 6.29TB on the array currently, so by replacing the 2TB disk I would have 3x8TB disks in the machine, and I would use two of them for parity drives and one of them as a data drive, and since it is 8TB, it should have enough space by itself. Does that make sense?

 

Yea, good idea to use the old 2TB disk for backups 👍

[itimpi]

18 minutes ago, Spewu said:

I think option 3 is possible because I only use 6.29TB on the array currently, so by replacing the 2TB disk I would have 3x8TB disks in the machine, and I would use two of them for parity drives and one of them as a data drive, and since it is 8TB, it should have enough space by itself. Does that make sense?

 

Yea, good idea to use the old 2TB disk for backups 👍

2 x parity for 1 data drive is horrible overkill for the number of drives - particularly if you have decent backups.   It tends to be more common to consider a second parity drive when you get up to something like 8-10 data drives.   In fact with good backups I would consider going the other way and running without any parity at all as that gives better performance.

[Spewu]

2 minutes ago, itimpi said:

2 x parity for 1 data drive is horrible overkill for the number of drives - particularly if you have decent backups.   It tends to be more common to consider a second parity drive when you get up to something like 8-10 data drives.   In fact with good backups I would consider going the other way and running without any parity at all as that gives better performance.

That is some really good input - thanks!

 

I did not consider the performance implications for this, so having two parity drives will naturally impact performance more than having 1 parity drive - really good point.

 

I do have cloud backups for my most important data, like family photos etc, but I do not have backups for everything in the array, and therefore I would like to keep at least one parity drive, so I am at least protected from a single drive failure. If the house burned down, then I would be sad loosing the data that was not backed up, but it would not be a big deal, so that is the reason I am not backing that up.

 

[itimpi]

7 minutes ago, Spewu said:

I did not consider the performance implications for this, so having two parity drives will naturally impact performance more than having 1 parity drive - really good point.

 

If you have a decent processor then the  2nd parity drive probably does not affect performance compared t' a single parity.   However running with no parity at all DOES improve performance.

 

It is also worth pointing out that having a parity drive does not mean that you cannot lose data - it is more about handling disk failure and giving high availability.  It also makes more sense when you have a lot of data drives so backups are more of an issue because of the space required    In your case with so few drives you could simply use one of the 8TB drives as a backup so the parity becomes less important.