Mix & Match Storage

[Raheel]

Hi Folks,

I am just getting started with FreeNAS and in the short term, I wish to use some of my existing drives. I have about 2 TB of data. I have a 3 TB and a 2 TB HDD. I plan on purchasing a 4TB HDD soon.

I am thinking of starting with a 4TB and a 3TB mirrored to each other. As I understand, this would give me a total capacity of 3TB. In the future I would like to get to four 4TB HDDs in RAIDz2.

What is the process of adding more storage (4TB HDDs) in the future and moving to RAIDz2? Is it simply changing the setting in FreeNAS and the system will take care of everything? or something more involved?

 

[Stux]

refresh your backup, reshape pool, restore from backup

You have a backup right?

 

[Raheel]

Backup is an external HDD.

 

[Stux]

Backup is an external HDD.

So, if you have mirrors, then you can keep on adding pairs of mirrors as often as you want, and when you can't add mirrors anymore, then you can replace your smallest mirrored pair of drives with a new set of larger drives... and you can keep on growing like that.

(technically, you can remove the second drive in a mirror and revert to a zero redundancy stripe)

BUT you can't convert mirrors into RaidZ vdevs, and you can't reshape a raidz vdev either (ie, add extra drives, remove drives, or increase the amount of parity)

So, if you want to convert from a pair of mirrors into a RaidZ1, then you have to reformat the drives as RaidZ1. And if you then want to add a few more disks and make a RaidZ2, then again, you have to reformat.

Sucks. But that's how it is.

BUT say you had Six disks in RaidZ2, and you wanted to add another 6 disks as RaidZ2. This you can do. But if you just wanted to add two more disks to the original RaidZ2, then you would have to reformat again.

Also, if you did add a second RaidZ2, and later you wanted to remove the first... that would again involve a reformat.

None of this is really a problem, other than the time taken to restore the data, since you should have a backup anyway...

You can get fancy, and play musical chairs with disks and data... For an example of the shananigans involved, see my "Lets Dance" instructions here:
https://forums.freenas.org/index.php?threads/freenas-ntfs-to-z-freenas-virgin.46243/#post-315359

 

[Raheel]

Thank you...that's very helpful!