New to FreeNAS, need help on hardware

[rockhead006]

I wasn't planning on having the 8 (7 actually) drives striped. But individual drives. And then having 3 drives in a RAIDz1 for storage of important data (which is also backed up to the non-RAID drives).

 

[garm]

Don’t use RAIDZ1 unless the drives are small with high MTBF , you are safer with mirrors.

If the backup is local I would use ZFS for that disk as well. There is a reasource for how to do that with external drives. The same logic applies to internal drives

 

[rockhead006]

Don’t use RAIDZ1 unless the drives are small with high MTBF , you are safer with mirrors.

Wouldn't RAIDz1 be better than a mirror. As it allows for a drive to fail, before you lose any data. I know a mirror does the same, but wouldn't RAIDz1 do the data integrity checking, to ensure no data has got corrupted also? I assume mirrors don't do this. Or do they?

 

[Johnnie Black]

I assume mirrors don't do this. Or do they?

They do.

 

[garm]

Wouldn't RAIDz1 be better than a mirror. As it allows for a drive to fail, before you lose any data. I know a mirror does the same, but wouldn't RAIDz1 do the data integrity checking, to ensure no data has got corrupted also? I assume mirrors don't do this. Or do they?

RAIDZ1 allows one of N disks is a vdev to fail (N=>3). You can use the space of approx N-1 drives. A mirror can loose N-1 drives and you get the space of 1 drive.

Data integrity checking is a function of ZFS and is always happening regardless of the percents of redundancy. Error correction requires redundancy.

 

[rockhead006]

So I currently have 6 x 3TB drives, and 6 x 2TB drives. Half of these drives are for backups of data, so only half are really in use.

I would like to initially buy 2 x 4TB drives, and put them into a RAIDz2 with the 6 x 3TB existing drives (and then over time upgrade them to all 4TB drives).
My only issue is there is data on (3 of the 3TB drives) that I need. So would need to somehow copy it off somewhere. As I think ZFS would wipe the drives when they are put into the RAIDz2.

I've calculated I have about 12.7TB in use over the drives. So I could move (most) of this data onto the 6x2TB drives (and the remaining 0.7TB somewhere else, I'm sure I have another drive somewhere which could hold this).
Then I could put the new 2 x 4TB drives, and the old 6 x 3TB drives into the new FreeNAS system, and set up a RAIDz2. Which should give me 14.17TB of space (assuming only 3TB of each drive can be used), so I can copy the data back to the new RAID array.

So, my questions would be:
- How do I do this, is it a simple GUI on FreeNAS?
- How much work is it to change from the old 3TB drive(s) to new 4TB drive(s) (when I buy new drives to replace the old)?
- How much work is it to add additional drives to a RAIDz2 array after it's already been set up? For example, if I wanted to put in 2 more 4TB drives.
- What is the likelihood of a RAIDz2 failing? Do you guys have RAIDz2 or RAIDz3 (or mirrors/other)?

 

[pro lamer]

Don’t use RAIDZ1 unless the drives are small with high MTBF

4 TB doesn't sound small...

- How much work is it to change from the old 3TB drive(s) to new 4TB drive(s) (when I buy new drives to replace the old)?

Just like replacing a failed drive, one at a time...

- How much work is it to add additional drives to a RAIDz2 array after it's already been set up? For example, if I wanted to put in 2 more 4TB drives.

Destroying a pool is needed. Or wait a few years until the new OpenZFS expand feature is incorporated into FreeNAS...

individual drives

I used to consider using some modern version of par2 based software for redundancy in individual drives...

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