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disable single fibre path

eran_6
Advisor

disable single fibre path

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
14 REPLIES
Mohamed K Ahmed
Trusted Contributor

Re: disable single fibre path

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

Mohamed
eran_6
Advisor

Re: disable single fibre path

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
Mohamed K Ahmed
Trusted Contributor

Re: disable single fibre path

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
Mohamed K Ahmed
Trusted Contributor

Re: disable single fibre path

eran_6
Advisor

Re: disable single fibre path

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
Mohamed K Ahmed
Trusted Contributor

Re: disable single fibre path

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

Mohamed
eran_6
Advisor

Re: disable single fibre path

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.
Hein van den Heuvel
Honored Contributor

Re: disable single fibre path

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.
eran_6
Advisor

Re: disable single fibre path

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
Ralf Puchner
Honored Contributor

Re: disable single fibre path

why not configure this on the SAN switch?
Help() { FirstReadManual(urgently); Go_to_it;; }
eran_6
Advisor

Re: disable single fibre path

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.
Hein van den Heuvel
Honored Contributor

Re: disable single fibre path

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.
eran_6
Advisor

Re: disable single fibre path

what do you mean by "put in primitives"?
Hein van den Heuvel
Honored Contributor

Re: disable single fibre path

> 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.