topic Re: disable single fibre path in Operating System - Tru64 Unix

disable single fibre path

eran_6 — Mon, 02 Feb 2004 08:57:14 GMT

is there a way to disable a single fibre path in a tru64 O/S?
with the command "hwmgr -show scsi -full -id xxx" i see 3 valid paths. How can i manually disable one of them?
thanks,
Yaron Shmarya
system team
Israel Credit Cards - CAL

Re: disable single fibre path

Mohamed K Ahmed — Mon, 02 Feb 2004 09:25:14 GMT

Can you please provide more info?
What is configuration, what is the id xxx device? ...

Mohamed

Re: disable single fibre path

eran_6 — Mon, 02 Feb 2004 09:35:17 GMT

the device is a disk in an EMC symmetrix storage. the device is reachable via 3 ports
for example:
> hwmgr -show scsi -full -id 222

device device
hwid type file
=======================
222 disk dsk62

Bus target lun path state
===============================
6 1 34 valid
7 0 34 valid
7 1 34 valid

i want to disable one of the valid paths

thanks

Re: disable single fibre path

Mohamed K Ahmed — Mon, 02 Feb 2004 09:45:40 GMT

I never done it before, but here is a solution
The only way is to use "hwmgr" to
delete the device and then scan it back in using "hwmgr -scan scsi". This
will bring it back as a different dsk but then you can use the "dsfmgr
-m

" to rename it back to dsk222. The drive(s) while you
are doing this to, cannot be in use or mounted while you do this.

check out this link
http://www.blacksheepnetworks.com/security/resources/tru64/3660.html

HTH

Mohamed

Re: disable single fibre path

Mohamed K Ahmed — Mon, 02 Feb 2004 09:57:17 GMT

check this one out too
http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51B_HTML/ARSFCATE/SCSDDRCH.HTM

look at chapter 3

Mohamed

Re: disable single fibre path

eran_6 — Mon, 02 Feb 2004 10:20:44 GMT

i'm afraid you misunderstood my intention.
i want to disable 1 path to the disk, but KEEP THE DISK AVAILABLE to the host.
the document does not mention that kind of operation.

regards,
yaron

Re: disable single fibre path

Mohamed K Ahmed — Mon, 02 Feb 2004 10:23:40 GMT

The document provides information to delete devices and then add them again, thus reseting their path

Mohamed

Re: disable single fibre path

eran_6 — Mon, 02 Feb 2004 10:29:10 GMT

my question, in other words, is if there is an equivalent command in tru64 to the following VMS command:
> set device $1$dga1000 /noenable/path=xxxxx

this command disables a path to a multipath disk, and the O/S can still access it via one of the remaining paths. no disk deletion is required.

Re: disable single fibre path

Hein van den Heuvel — Mon, 02 Feb 2004 11:07:31 GMT

Please explain to us what you intend to achieve by reducing the availability and performance potential of your system?!
How does that help you or your system?

(I know one reason, but I'll wait for your input first :-).

This may be better solved on the Storage side. If this was on an EVA then I would just not present the unit to that adapter wwid. Surely EMC has something along those lines?

Hein.

Re: disable single fibre path

eran_6 — Tue, 03 Feb 2004 02:28:33 GMT

the reason for the path reduction is to perform a maintenance operation. each path represents a fibre port in the EMC symmetrix. we suspect that one of the ports should be replaced. we want to disable any transmissions on that path, but leave the disk available to the other paths.

thanks,
yaron

Re: disable single fibre path

Ralf Puchner — Tue, 03 Feb 2004 02:39:56 GMT

why not configure this on the SAN switch?

Re: disable single fibre path

eran_6 — Tue, 03 Feb 2004 10:36:50 GMT

i prefer to perform an O/S related action (if there is a way), instead of external action such as abruptly blocking the port in the switch.

Re: disable single fibre path

Hein van den Heuvel — Tue, 03 Feb 2004 10:57:29 GMT

Nah, just jank the cable.
It's made to handle that.
Seriously!

I agree with you that it would be kinda nice
to warn the system to stop doing IOs over the path about to be disrupted but it really should handle it.

The CAM/SCSI layer engineers agree with that and have put in primitives, but to date there is no API in Tru64 to do this 'nicely'.

My compromise would be to select a low-usage moment.

hth,
Hein.

Re: disable single fibre path

eran_6 — Tue, 03 Feb 2004 11:24:12 GMT

what do you mean by "put in primitives"?

Re: disable single fibre path

Hein van den Heuvel — Tue, 03 Feb 2004 23:34:34 GMT

> what do you mean by "put in primitives"?

That the lowest levels of the code would be readily adapted to gently deactivate a channel on request, but there is no way to get there from here today. And giving the current Tru64 plans don't hold your breath waiting for it to happen. HPUX maybe.

btw... Just poking a control structure will not do. (I asked :-).

Hein.