FibreChannel Stuff

Wed Sep 21 12:14:59 PDT 2005

When people talk about fiberchannel, what they are usually talking about
is SCSI encapsulated in the FC protocol. It is possible to run other
protocols encapsulated within FC, for instance, IP.

As you have suspected, many fiberchannel HBAs that are not "supported"
will work just fine, as the basic fiberchannel standard, and that of
SCSI have been well defined for quite a while. Non-supported cards
usually just have not been tested extensively. This typically means you
are on your own when a problem arises.

The relevant question is: How important is it to me to be able to get
support for my configuration from my array vendor when I have a problem?
You have suggested that this is going to be a production system. Are you
going to be capable of debugging and fixing problems on your own?

If you do decide to jump into an unsupported configuration, go with the
HBA that your OS has a stable driver for. Take a look at Emulex, too. We
are using a few Redhat machines with Emulex LP9000 series cards with
good luck, and have generally found them to be quite reliable and widely
applicable.

Are you willing (or is it even possible) to change the OS in question?
You may find more supported options when dealing with something like
Redhat ES, or Solaris. I have not personally used FreeBSD on my SANs.

Are you planning to use this system "direct attached" via a fiber
channel arbitrated loop (FCAL) or through a switched fabric SAN?

-jimk

-----Original Message-----
From: owner-baylisa at baylisa.org [mailto:owner-baylisa at baylisa.org] On
Behalf Of Danny Howard
Sent: Wednesday, September 21, 2005 11:00 AM
To: baylisa at baylisa.org
Subject: FibreChannel Stuff

Hello,

This is a sufficiently different question from my last question that I
figured I'd send a new  thread out. :)

WHAT'S WITH FIBRECHANNEL?  My understanding is its basically another
generation of SCSI, with a more complicated set of connectors.  But
whenever I look at a disk appliance, there's a list, usually a very very
very very very short list of supported HBAs.

For example, if I want an Apple Xserve RAID, the supported non-Mac HBA
is the LSI7202XP.  Okay ... well, what if my server OS doesn't have a
driver for the HBA?  Can I try a different HBA?  Isn't the point of
FC to be a standard to connect bits of hardware together and have them
interoperate?  So, does an "unsupported" HBA just not work?  Or is
"supported" merely a means of saying "yes, we have tested it to some
degree, and maybe got some money from our partner, and bless this one
HBA?"

IF I have the temerity to use a non-"supported" HBA ... do things
usually still work?  Or is FC some delicate twitchy thing where if I
can only reliably connect bits together only after the hardware vendors
have collud^H^Haborated sufficiently to work out all the subtle little
bugs in the FC standards that only creep out under high loads, or such?

Lastly, are there any FreeBSD admins on here who use FC HBAs in a
production environment, and could vouch for or reccoment particular
solutions?

Thanks again.

Sincerely,
-danny

-- 
http://dannyman.toldme.com/