Date: Thu, 10 May 2012 07:31:01 -0700 From: Trent Nelson <trent@snakebite.org> To: "mj@feral.com" <mj@feral.com> Cc: "freebsd-scsi@freebsd.org" <freebsd-scsi@freebsd.org> Subject: isp target mode bugs? (was Re: Missing sysctl options for isp driver) Message-ID: <079A4619-38CC-443D-A191-3481819BEBB8@snakebite.org> In-Reply-To: <4FA28976.2070607@feral.com> References: <20120502203948.GA1141@snakebite.org> <4FA1DF1C.2030706@feral.com> <20120503050956.GA18983@snakebite.org> <4FA28976.2070607@feral.com>
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> > > FreeBSD is the most up to date, but certainly has bugs in target mode=
.=20
> > I, uh, I don't think I'm using target mode. I've got four Xyratex RS-=
=20
> > 1600-FC2 JBODs (16x146GB + 48x36GB) connected to two-but-soon-to-be-fou=
r
> > HP StorageWorks SAN Switch 2/16s. Each FreeBSD box has a minimum of tw=
o
> > FC HBA ports; each HBA port goes to a different switch, and zoning conf=
ig
> > on the switches controls which disks each hosts sees (although more on
> > this later).
> > So, uh, I think that constitutes fabric mode right? The switch reports
> Target Mode is where the FreeBSD box can pretend to be a disk. Yes,
> that's fabric.
I disregarded target mode when I read your explanation, thinking it
wasn't relevant to my environment.
However, it dawned on me this morning how useful this could be. Every
box on my network has a minimum of two FC HBAs, and they're all capable
of booting from an FC drive. Other than the amd64 FreeBSD boxes, every=
-
thing else is non-PC (SPARC, IA64, Power4+, PA-RISC etc).
Having had an absolutely woeful experience with the Mylex FFx2 RAID=20
controller intended for the Xyratex enclosures, I've since decided to
ditch it an leverage ZFS + JBOD instead.
However, it's been bothering me a little bit that all the non-ZFS hosts
wouldn't benefit from, er, ZFS. I'd have to set up mirrored root volum=
es
and all that crap to get a similar level of redundancy, but I'd be miss=
ing
all the ZFS Good Stuff.
I was planning on leveraging iSCSI (via zfs volumes), which would allow=
me
to export ZFS-backed disks to non-ZFS hosts, but I'd really be only abl=
e
to use those volumes for (non-important) data -- I couldn't boot off th=
em
nor have them as primary OS disks (limitation of old-ish hardware).
As every box on the network has two FC HBAs, I found myself thinking th=
is
morning how useful it would be if I could present zfs volumes as disks =
to
the SAN fabric, then zone/allocate them as if they were JBODs.
....ergo, target mode!
=20
Which makes your comment below all the more interesting:
> > > FreeBSD is the most up to date, but certainly has bugs in target mode=
.=20
What sort of bugs are we talking about? ;-)
=20
I'm pretty keen to explore this route after this morning's revelation. =
I
could boot all my AIX/HP-UX/etc boxes off ZFS-backed volumes; which mea=
ns
I could snapshot, clone, rollback, compress, dedup etc behind the scene=
s.
Which would be absolutely bad-ass.
What are your thoughts on this? Viable option or are there fundamental=
,
insurmountable technical issues that'll make my life miserable?
Trent.
56,1 =
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