ZFS, Zvol, iSCSI and windows

[Tom Curry]

On Fri, Oct 2, 2015 at 4:24 AM, Willem Jan Withagen <wjw at digiware.nl> wrote:

>
> So the moral of the story:
> It is not always wise to match NTFS blocksize with the ZVOL blocksize.
>
> As for possible performance penalties on the Windows side....
> It is hard to find a niche and sensible disk tester.
>
> Using the error scanner from HDtune, performance has dropped a tiny bit.
> I'm seeing a 1000 IOPS and 30Mbyte/sec of throuput.
> This is on a 2* vdev 6* disk raidz2 volume.
>
> --WjW
>

Well if space efficiency is the goal then the moral of the story should be
when using a fixed block/stripe size (as is the case with a zvol) make sure
the size is at least as large as the sum of all non parity/mirror disks in
a vdev. I think this holds true for any vdev configuration, be it a stripe,
mirror or parity.

As for the NTFS cluster size, in my travels I haven't been able to notice
any real performance or efficiency difference when changing the cluster
size. Perhaps a little variance at extremes, but nothing worth getting
excited over.