Fibrechannel support in 4.9 ?

[Jonathan Fosburgh]

On Wednesday 12 November 2003 01:19 pm, Pete French wrote:
> > Welcome to the world of SAN. :) Someone else has already provided
> > FreeBSD-specific info, here's a few other pieces of the puzzle for you. 
> > In attaching a FC RAID array you will be creating a small point-to-point
> > fibre channel network (a small SAN).  Internally the array is probably
>
> O.K. - is that going to be affected by the fact that there will be a number
> of other machines also attached to the array ? Got 2 BSD machines for
> starters and possibly 5 windows machines. I am unsure of FC topology - will
> all of them be point-ot-point into the array ?
>

Well now you're making things complicated. :) Will this be concurrent access 
(everyone accessing the same data, I think not but have to ask) or are you 
carving out multiple LUNs on the array?  If the former, you'll need to ask 
more questions here about doing concurrent access to disk from multiple 
hosts.  If the latter then there shouldn't be a problem, at least in theory.  

How will the multiple hosts be attached?  Does the array allow multiple HBAs 
or will you be connected through a switch? If you're going through a switch 
then the switch vendor (Cisco, Brocade, CNT, McData, etc) should provide you 
with supported HBAs for different platforms.  Match that against the 
supported HBAs for FreeBSD and hopefully there is at least one in common.  

As to topology, more than likely all will work as P2P.  However, in our SAN 
(>12TB, 60+ hosts) a portion of the Windows servers connect as loop 
(henceforth abbreviated as FC-AL), but our switches support that.  You'll 
have to research your particular hardware to make that determination.  They 
should state what modes of connection are supported, and now that I think 
about, I remember that some disk servers do require direct connections (not 
through a switch) to be FC-AL, so, again, do your research. :)

If you are using a switch, zoning is a must.  Do not, under any circumstances, 
place Windows and any other OS in the same zone.  Windows does not play fair, 
and will attempt to configure the other HBAs in that zone.  Best practice is 
to zone each Windows HBA seperately.  (I have ~50 zones for 25 Windows 
servers across two switches.  It's a pain but basically its required.)

> > arbitrated-loop, but that should not be a concern to you.  Fibre Channel
> > is a
>
> Makes mental note to go research arbitrated-lopp vs point-to-point! Does
> this affect the kind of card I acquire ? Will all of them boot fine ?

You probably have three options for HBAs.  Some are P2P only, some are FC-AL 
only, and some are either-or.  Personally, I would go for an either-or card 
if you can do it.  QLogic cards let you force to one or the other in the 
BIOS.   I *think* that the ability to boot over FC is partially dependent on 
the firmware on the HBA (in addition to OS support), so, again, there is 
something for you to research. 

>
> > networking architecture that allows transport of other protocols, usually
> > SCSI (FCP).  Curtis Preston's _Introduction to SAN and NAS_ (published by
>
> O.K., that helps a lot - if its just acting as an alternative SCSI
> transport as far as th OS ins concerend then that makes me a lot happier.
> Thanks for the advice.

If I had to make a guess, I would think your LUNs will show up as daX, and you 
basically manipulate them as you would any SCSI disk. 

I know I've given you a lot to research, but, trust me, it is better to go 
through this before the hardware is in place than to have everything in-house 
and run into problems.  We've had people purchase unsupported HBAs that 
(big-surprise) didn't work because they didn't come to us first.  We've had 
issues with firmware incompatibilities that were not discovered until over a 
month into the project.  Doing the work beforehand will save you a lot of 
headaches.  Good luck. :)

-- 
Jonathan Fosburgh
AIX and Storage Administrator
UT MD Anderson Cancer Center
Houston, TX