PBS 4: ZFS raidz2 - live expansion possible?

[sherminator]

Hi there,

does PBS 4 include a ZFS version that allows live expansion of a raidz2 pool with an additional disk? If so, has anyone successfully tried this yet?

Thanks and greets
Stephan

 

[news]

try it! use the openZFS feature.

# https://openzfs.org/w/images/5/5e/RAIDZ_Expansion_2023.pdf
# https://freebsdfoundation.org/blog/openzfs-raid-z-expansion-a-new-era-in-storage-flexibility/

you can setup a files based zfs pool raidz2 and then test it.

See this forum for more.

 

[sherminator]

thanks! So I will go shopping and trying - and letting you know how it went.

 

[waltar]

It will went ... but slower as before when expansion (which is even really slow) is done. Remember you are talking about extent a raidz2 pool with a single disk so even assume you have a single vdev. PBS needs iops which isn't the case a raidz(*) is good at and with higher capa in the vdev you get even more chunk files while the iops are that of a single disk in that vdev ... and your iops are need to scale with scaling files but wouldn't !!

 

[sherminator]

It will went ... but slower as before when expansion (which is even really slow) is done. Remember you are talking about extent a raidz2 pool with a single disk so even assume you have a single vdev. PBS needs iops which isn't the case a raidz(*) is good at and with higher capa in the vdev you get even more chunk files while the iops are that of a single disk in that vdev ... and your iops are need to scale with scaling files but wouldn't !!

yes, you're right, it's a single vdev. Of course more vdevs gives you better performance - and are more expensive when achieving the same level of redundancy.
In real life we're quite happy with our backup storage performance. We write backups with about 1 GB/s, and we read (aka restore) backups with about 2 GB/s. In a datastore containing about 50 TB of backup data.