RAIDZ1-0 Expansion

[dr_sherman]

Hi All,

Got a fairly simple question but I have been slightly confused by some of the information that I have come across within the forums so I thought I would quickly ask the question!

I currently have a raidz1-0 consisting of x4 4TB drives which has become unhappy as I have used 95% of the capacity. I understand that in the event of a single drive failure I should not lose any data. If I add in a 5th 4TB drive and expand the pool will I retain the same protection across the entire pool?

Thanks,

 

[anodos]

Hi All,

Got a fairly simple question but I have been slightly confused by some of the information that I have come across within the forums so I thought I would quickly ask the question!

I currently have a raidz1-0 consisting of x4 4TB drives which has become unhappy as I have used 95% of the capacity. I understand that in the event of a single drive failure I should not lose any data. If I add in a 5th 4TB drive and expand the pool will I retain the same protection across the entire pool?

Thanks,

No. You will have a zpool consisting of two striped vdevs (one 4-disk RAIDZ1 vdev and one single-disk vdev). Failure of a vdev results in failure of zpool, which causes loss of all data. See slideshow here: https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

 

[dr_sherman]

No. You will have a zpool consisting of two striped vdevs (one 4-disk RAIDZ1 vdev and one single-disk vdev). Failure of a vdev results in failure of zpool, which causes loss of all data. See slideshow here: https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

Thanks anodos - appreciated.

 

[danb35]

As @anodos said, you can't simply add a single disk to your pool and still retain redundancy. In the resulting pool, the newly-added disk would be critical--failure of the new disk would destroy all your data. Failure of one of any of the other disks would still be tolerated.

To increase your pool's capacity, while retaining redundancy, you have three options:

• Replace each disk, one at a time, with a larger disk
• Add a new, redundant vdev (i.e., consisting of two or more disks)
• Back up your data, destroy the pool, re-create it with more disks, and restore the data

RAIDZ1 isn't recommended with modern high-capacity disks.