ZFS Raid Level

[olsenblane]

I have spent a couple of hours trying to review ZFS protection levels, but couldnt find anything that indicates the level of protection I have setup.
I have 6 x 6TB Red Drives, and just lost one drive the other day. Looking at the attached output of zpool status , what happens if I lose another drive before I replace that dead drive? Can I lose another drive in the same mirror, or am I protected across the entire pool?

I use this as a file server and Plex Server, and its funny how I had a WD Red Drive go out in less than a year, yet my cheaper WD Blue and Green drives that served a similar purpose, have been living for 5+ years

 

[MikeyG]

If you lose the other drive in mirror-2 your pool will be offline and if the disks are bad, you will lose all the data on the pool.

You can take a single drive loss to both mirror-0 and mirror-1 and keep on ticking.

 

[olsenblane]

@mgittelman Thank You!
This is just an assumption, but I assume I can add additional drives to each mirror to increase redundancy, or create additional 2-drive mirrors to increase capacity and pool performance?

 

[Chris Moore]

You can replace the failed drive by a process called resilvering.
You can extend the pool with additional mirror vdevs to grow capacity.
Adding another drive to each mirror to create 3-way mirror vdevs from the simple mirror vdevs you have, it's possible, but it's not simple because it's done from the command line.
If you want to go with that, I can direct you to the instructions.

 

[Evertb1]

If you lose the other drive in mirror-2 you must assume that your pool is gone not just offline! I feel that if you are willing to sacrifice a big part of your raw storage capacity for redundancy you might be better of with a RAIDZ-2 or even RAIDZ-3 configuration. That way you can lose any 2 or 3 disks before you are in real trouble. Anyway, if you love your data you should be already busy with replacing the failed disk. In my opinion it's better to take care that you get in save territory again before you look at changing your configuration. I do hope you have a decent backup plan.

 

[olsenblane]

Lol, yes, I do have various backup mechanisms in place, and am just waiting for the RMA for the drive to be completed.
Once I have replaced my drive, is it possible to convert my Mirrors into RaidZ-2 or 3? Or will that require a new pool to be created and data migration?
Last question- will I be sacrificing any disk performance by going to RaidZ-2 or 3 vs the current drive mirrors I have now? I am fine with reducing some disk IO for redundancy, but I dont want a 6-drive array to have the performance of a single drive, which I vaguely remember reading that certain disk configurations act this way.

 

[Chris Moore]

For the description of the use, the reduced performance should be near undetectable, unless you have a 10Gb network.

 

[Evertb1]

Lol, yes, I do have various backup mechanisms in place, and am just waiting for the RMA for the drive to be completed.
Once I have replaced my drive, is it possible to convert my Mirrors into RaidZ-2 or 3? Or will that require a new pool to be created and data migration?
Last question- will I be sacrificing any disk performance by going to RaidZ-2 or 3 vs the current drive mirrors I have now? I am fine with reducing some disk IO for redundancy, but I don't want a 6-drive array to have the performance of a single drive, which I vaguely remember reading that certain disk configurations act this way.

Good that you have your backups taken care of. Because while you are waiting for that RMA you are at a higher risk level. It's a pity but you can't convert your pool. You need to build a new one. As far as the performance goes, take note of what @Chris Moore said about that.