iSCSI/ZVOL: ZFS or UFS on the initiator side?

Patrick M. Hausen hausen at
Fri Apr 7 15:04:53 UTC 2017

Hi, all,

a general question:

If I export a ZVOL via iSCSI to be used be another FreeBSD
machine as a block device, is it advisable to use ZFS or should
I stick to UFS?

I don't have any reason to believe that ZFS might be harmful.
I just know from experience, that e.g. tunneling TCP through
TCP can lead to strange effects if you happen to really have
packet-loss. Anything similar for ZFS in ZFS?

What if iSCSI target (ZVOL) and initiator are on the same machine?
They'll share ZIL and ARC. What if memory gets low?

I'm investigatiing the feasibility of creating a HA setup by
running a mirror (ZFS or gmirror/UFS) on top of 2 iSCSI ZVOLs,
one on the local machine but still via ISCSI, one on a remote
machine ...

TIA for your opinion and advice,
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