[geeks] Linux Fibre Channel and Hotplug question

[Ido Dubrawsky]

Ok...a bit of an update.  I was able to get one of the presented LUNs working
and mounted as a disk to one of the 4 servers I'm trying to attach to this SAN.

My question now focuses on the fact that udev/hotplug do not seem to be working
at all.  Supposedly, when the LUN is presented to the server (and I can see it
in lputil as well as the hbanywhere software), udev should create an entry in
/sys/block for the device.  Then it will create the device file in /dev.  The
problem is that udev/hotplug do not seem to be doing this as dynamically as
they claim they can.  It appears that in some instances I have to reboot the
box in order to get udev to do what it's supposed to do.  I've created the 
following file in /etc/udev/rules.d (in a file called 20-scsi.rules):

KERNEL="sd*", BUS="scsi", PROGRAM="/sbin/scsi_id", SYMLINK="disk-%c%n"

And I change the entry in /etc/scsi_id.config to:

options=-g

in order to mark all devices as good.

I then run udevstart in order to get udev to rescan the sys directory for new
entries and create the appropriate device files in /dev.  The problem is that
the entry for the new device, /sys/block/sda, does not get created in /sys
once the LUN is presented.  It appears that the system must be rebooted (I
suspect...our next maintenance window is this afternoon and I will be able
to cycle two more servers to see if they see the newly presented LUNs this 
time).  The problem is that this was not necessary (so far as I remember when
I did this last week with the first of the four servers...it appeared to see
the LUN immediately).  Can someone point me to some decent documentation (which
probably doesn't exist) for udev/hotplug to see if I can debug this?  Does 
anyone have any suggestions.  

It appears from all my tinkering that the second server I tried to attach to 
the SAN just won't create the device file.  I suspect it may have to do with the
fact that I originally built it to run Xen but that once VMware released the
Server product for free (which, by the way, I heard from VMware that it /will/
remain free from here on out) we decided to switch to VMware.  I've removed the
Xen components but there could be cruft still in the system.  So, it looks
like I'm going to kickstart that box again.  Fortunately the data partition is
on a separate RAID disk so I can preserver alot of things and do the install
without too much trouble.

Any ideas?

Ido

P.S.  The customer I'm working at right now, the Congressional Research Service
at the Library of Congress will be opening one (possibly two) position(s) for
a permanant network administrator next month.  They're looking for someone
who's got experience with Linux/UNIX along with Cisco experience (they've got
some switches -- a 4006 and some 2950s -- a LocalDirector 413 and a Cisco
Content Switch -- and it looks like they're going to be growing over the next
few years) and Windows/Novell experience (secondarily).  Let me know if you're
interested and I'll send out the link to the posting.  The people here are 
really nice and the manager is very nice -- salt of the earth kind of a guy.
It's not for me as I'm more focused on security but it's been a nice diversion.
I will be moving on (possibly with AT&T...possibly somewhere else) but I'm 
staying in the D.C. metro area.
-- 
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Ido Dubrawsky, CISSP           		E-mail:          ido at dubrawsky.org
Network Security Architect			   idubraws at siliconsec.com
dubrawsky.org
500 Hermleigh Rd
Silver Spring, MD. 20902
(301) 651-5441 (cell)
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