zfs discuss - May 2007 - shareiscsi is cool, but what about sharefc or sharescsi?

I''d love to be able to server zvols out as SCSI or FC targets.  Are
there any plans to add this to ZFS?  That would be amazingly awesome.

-brian
-- 
"Perl can be fast and elegant as much as J2EE can be fast and elegant.
In the hands of a skilled artisan, it can and does happen; it''s just
that most of the shit out there is built by people who''d be better
suited to making sure that my burger is cooked thoroughly."  -- Jonathan
Patschke

> I''d love to be able to server zvols out as SCSI or FC
> targets.  Are
> there any plans to add this to ZFS?  That would be
> amazingly awesome.
Can one use a spare SCSI or FC controller as if it were a target?

Even if the hardware is capable, I don''t see what you describe as
a ZFS thing really; it isn''t for iSCSI, except that ZFS supports
a shareiscsi option (and property?) by "knowing" how to tell the
iSCSI server to do the right thing.

That is, there would have to be something like an iSCSI server
except that it "listened" on an otherwise unused SCSI or FC
interface.

I think that would require not just the daemon but probably new
driver facilities as well.  Given that one can run IP over FC,
it seems to me that in principle it ought to be possible, at least
for FC.  Not so sure about SCSI.

Also not sure about performance.  I suspect even high-end SAN controllers
have a bit more latency than the underlying drives.  And this is a
general-purpose
OS we''re talking about doing this to; I don''t know that it
would be acceptably close,
or as robust (depending on the hardware) as a high-end FC SAN, although it might
be
possible to be a good deal cheaper.
 
 
This message posted from opensolaris.org

On Jun 1, 2007, at 18:37, Richard L. Hamilton wrote:
> Can one use a spare SCSI or FC controller as if it were a target?
we''d need an FC or SCSI target mode driver in Solaris .. let''s
just
say we
used to have one, and leave it mysteriously there.  smart idea though!

---
.je
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On Fri, Jun 01, 2007 at 06:37:21PM -0700, Richard L. Hamilton
wrote:
> > I''d love to be able to server zvols out as SCSI or FC
> > targets.  Are
> > there any plans to add this to ZFS?  That would be
> > amazingly awesome.
> 
> Can one use a spare SCSI or FC controller as if it were a target?
Most definitely.  FreeBSD already has an FC Target Mode (which
they''ve had for a while, don''t know about SCSI Target Mode)
> Even if the hardware is capable, I don''t see what you describe as
> a ZFS thing really; it isn''t for iSCSI, except that ZFS supports
> a shareiscsi option (and property?) by "knowing" how to tell the
> iSCSI server to do the right thing.
> 
> That is, there would have to be something like an iSCSI server
> except that it "listened" on an otherwise unused SCSI or FC
> interface.
Ohhhhh, I hadn''t thought of it that way.  So the FC/SCSI Target Mode
would have to exist independent of ZFS and the just allow ZFS to hook
into its configuration like it does iSCSI.   Hmmmmm.
> I think that would require not just the daemon but probably new
> driver facilities as well.  Given that one can run IP over FC,
> it seems to me that in principle it ought to be possible, at least
> for FC.  Not so sure about SCSI.
I''ll have to poke around and see how FreeBSD does it and look at the
Solaris
iSCSI stuff, that could be interesting.
> Also not sure about performance.  I suspect even high-end SAN controllers
> have a bit more latency than the underlying drives.  And this is a
general-purpose
> OS we''re talking about doing this to; I don''t know that
it would be acceptably close,
> or as robust (depending on the hardware) as a high-end FC SAN, although it
might be
> possible to be a good deal cheaper.
In my case performance is the least of my worries.  I''m looking to get
such things as VAXen and PDP-11s pointed at a small SCSI "disk". 
Small
SCSI disks are hard to find and ready to die.  Most of the PDP-11 OSes
wouldn''t know what to do with 300GB of disk space.  a nice 4G (or
smaller) FC/SCSI Target disk would be perfect as it would be a drop in
the bucket of my ZFS Pool, and would also allow for a nice redundant
"disk" for the older hardware.

Just a thought. :)

-brian
-- 
"Perl can be fast and elegant as much as J2EE can be fast and elegant.
In the hands of a skilled artisan, it can and does happen; it''s just
that most of the shit out there is built by people who''d be better
suited to making sure that my burger is cooked thoroughly."  -- Jonathan
Patschke