ZFS pool in an ISCSI ZVOL
By user12625760 on Apr 20, 2007
My last post about backing up ZFS on my laptop to iscsi targets exported from a server backed by ZFS Zvols on the server prompted a commend and also promoted me to think about whether this would be a worth while thing in the real world?
Initially I would say no, however it does offer the tantalizing possibility to allow the administrator of the system with the iscsi targets to take back ups of the pools without interfering with the contents of the pool at all.
It allows you to split the snapshots for users, which would all live in the client pool from the snapshots for administrators, essentially for disaster recovery which would all be in the server pool.
If the server went pop the recovery would be to create a new server and then restore the zvol which would then contain the whole client pool with all the client pool's snapshots. Similarly if the client pool were to become corrupted you could roll it back to a good state by rolling back the ZVOL on the server pool. Now clearly the selling point of ZFS is an always consistent on disk format so this is less of a risk than with other file systems (unless there are bugs) however the belt and braces approach seems appealing to the latent sysadmin in me who knows that the performance of a storage system that has lost your data is zero.
I'm going to see if I can build a server like this to see how well it performs but that won't be for at least a few weeks.