On 31 Jan 2008, at 21:43, dbcooper wrote:
Domenico, (and everyone else thanks)
Thank you for your input. This seems to be a deeper rabbit hole than
I expected.
I tried (echo "1" > /sys/bus/scsi/drivers/sd/<SCSI-ID>/delete) and
sure enough it cleanly wiped out the /dev/sdc and the /sys/block/
device etc. Upon reboot, it was back and had the same old Buffer I/
O errors and block errors on reboot and recreated the same /dev/sdc
etc.
So I started digging through the udev / udevinfo commands and
comparing with lspci to find that yes the ghost /dev/sdc was hanging
(supposedly) off my Qlogic Fiber Card, I then launched my Navisphere
to make sure it only had one LUN being handed out (and it is). So I
got even more confused. I've not got much SAN experince and I was
handed this with my servers. I then took a look at the SANSurfer Cli
tool (sfcli), I was able to see that the HBA does see (looks like
it) 2 LUNS of exaclty the same size (I.E. it's really just the one I
guess).
A barrage of questions:
Whose QLogic drivers are you using? Do you have multiple Fibre cards
in the system? Is your QLogic card dual-port? Do you have multiple SAN
switches?
This sounds to me very like our systems would look when we have two
SAN paths to the same LUN (i.e. redundant fibre cards and a redundant
fabric). Unless you are using QLogic drivers that natively understand
Multipathing (it's an option - Red Hat's ship without as the preferred
method is dm-multipath - HPs (just as an example) ship with it turned
on so you don't need dm-multipath.)
--
Sam
The LUN that is being presented to the machine is being mounted as
sdd. (the offender I'm hunting down is sdc).
Do you think it's possible that when I delete the sdc with the above
"echo 1" you suggested and reboot, that the kernel is trying to
assign the presented LUN as the next device in line sdc? (since sda,
sdb and sdd are taken).
I don't know anything about the persistent binding (yet) but I'll be
going through all the docs from the Qlogic and EMC products tomorrow
(now that I know what to start looking at).
Thanks for any other advice (if you can suggest any).
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