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>
next in thread | previous in thread | raw e-mail | index | archive | help
> > > FreeBSD is the most up to date, but certainly has bugs in target mode.
> > I, uh, I don't think I'm using target mode. I've got four Xyratex RS-
> > 1600-FC2 JBODs (16x146GB + 48x36GB) connected to two-but-soon-to-be-four
> > HP StorageWorks SAN Switch 2/16s. Each FreeBSD box has a minimum of two
> > FC HBA ports; each HBA port goes to a different switch, and zoning config
> > 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
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 volumes
and all that crap to get a similar level of redundancy, but I'd be missing
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 able
to use those volumes for (non-important) data -- I couldn't boot off them
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 this
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!
Which makes your comment below all the more interesting:
> > > FreeBSD is the most up to date, but certainly has bugs in target mode.
What sort of bugs are we talking about? ;-)
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 means
I could snapshot, clone, rollback, compress, dedup etc behind the scenes.
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 Bot
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?079A4619-38CC-443D-A191-3481819BEBB8>