Converting a data drive into a parity drive without data loss

[drumstyx]

My setup: 2x 4TB IronWolf drives, 1x 4TB WD desktop drive, 1x 1TB WD desktop drive.

 

One of the 4TB IronWolf drives is my current parity, and the other is currently loaded right up with data. I have 2x 3TB drives I want to add as data drives, and I'd like to make that other IronWolf a second parity drive.

 

So I'm assuming I should add the new drives first, then transfer the data from the 4TB drive to the other drives in the array? How do I do this? From an outside perspective (Plex, for example) will everything stay as it is directory-wise?

[burtjr]

As long as your pointing plex to the user shares in /mnt/user should be no issues.

[trurl]

17 hours ago, drumstyx said:

How do I do this?

Maybe the unBalance plugin can help. I usually just use Midnight Commander.

[SSD]

Are the 3T drives older drives that you are putting back in service? If so, I'd look closely at their SMART reports before and after preclearing them.

 

Personally I wouldn't do it. Buy a new 4T+ drive and add as second parity. Or stick with single parity. Add the 3Ts as data after preclearing if you need the space. Your switching over will probably be more risk all at once than the reduced risk of the second parity would provide in its lifetime. ?

[trurl]

3 minutes ago, bjp999 said:

Are the 3T drives older drives that you are putting back in service? If so, I'd look closely at their SMART reports before and after preclearing them.

 

Personally I wouldn't do it. Buy a new 4T+ drive and add as second parity. Or stick with single parity. Add the 3Ts as data after preclearing if you need the space. Your switching over will probably be more risk all at once than the reduced risk of the second parity would provide in its lifetime. ?

I agree with this.

 

You don't have enough drives for parity2 to give a large benefit.

[SSD]

Other option is to use one or both of the 3T drives as backup disks. You could backup your entire array. A backup is infinitely better than a second parity disk. Now if your had 20 disks in your array, you might argue that using a second parity would provide a modicum of protection to any one of the 20, and might therefore be better than using that space to backup just a single disk.

[Frank1940]

On 4/8/2017 at 3:27 PM, drumstyx said:

One of the 4TB IronWolf drives is my current parity, and the other is currently loaded right up with data. I have 2x 3TB drives I want to add as data drives, and I'd like to make that other IronWolf a second parity drive.

You might want to read through this thread:

It is your decision in the end, but with such a small number of data drives, the chances of any data loss is very low with single parity if you run monthly parity checks and monitor the array between those checks.  A offsite backup of irreplaceable data would be a far wiser choice.