enlarging a ZFS file system

Christian Baer christian.baer at uni-dortmund.de
Fri Jan 25 14:43:55 UTC 2019

Hey again everyone!

I have a system with 5 drives running a RAIDZ2. The file system is 
getting a little cramped, so I would like to extend it.

Ideally I'd like to add 2 or three (identical) drives to the pool, let 
the system work a little and then have a result as if I'd created the 
whole thing from the start with 7 or 8 drives. Just to be clear: The 
result should be a RAIDZ2 with 7 or 8 drives (depending on how many I add).

A couple of years back, I read up on if this were possible and the only 
way to enlarge a RAIDZ at the time was to replace *all* the existing 
drives piece by piece with bigger ones and let the RAID heal drive by 
drive. During my research I did stumble on a thread where developers of 
ZFS were discussing that what I would like to do was actually a good 
idea and a relatively widely requested feature. I didn't participate in 
the discussion and for some reason cannot find it anymore. I must admit 
that I didn't save the URL at the time. :-(

Has there been any development in this direction? Can what I'd like to 
do be done with FreeBSD today? The drives in question are used for 
archive purposes and don't really see much action, so I am not worried 
that they will die it the data on them gets copied around a fair bit.

Y'all have a nice weekend! ;-)


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