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I/O is not affected due to both path failed

Surajit
Occasional Visitor

I/O is not affected due to both path failed

Hi, I am using HP-UX 11.11 and Hitachi storage and using PV Link as multipath software. When I have disabled both primary path and alternate path of storage, still the I/O is running. Can Any body help me or tell me why the I/O job is not affected due to fail of both the primary and alternate path. What is the solution for this ? So that my I/O job should be affected after disabling the both Primary and alternate path.
11 REPLIES
Turgay Cavdar
Honored Contributor

Re: I/O is not affected due to both path failed

If all paths failed actually it means no possibility for io... Are you sure that you disable the paths? How did you disable paths? How did you see that IO is still going to disk?
Ganesan R
Honored Contributor

Re: I/O is not affected due to both path failed

Hi Surajit,

You didn't mentioned how did you disabled both primary and alternate paths.

Have you disconnected the physical cable?
or any other way?
Best wishes,

Ganesh.
Surajit
Occasional Visitor

Re: I/O is not affected due to both path failed

Hi,
I have disconnected the both cables from the storage and I have run a script which is continuously making and removing directory and subdirectory on the file system of storage LUN. I have configured 10 nos LUN from the storage and made 3 file system on these storage LUN and run the script which is a I/O data beater.
Turgay Cavdar
Honored Contributor

Re: I/O is not affected due to both path failed

So did you see any IO activity on the disk, did you use sar -d or glance or just see the script output? Possible your script doesnt give you correct usage values...
Lijeesh N G_1
Respected Contributor

Re: I/O is not affected due to both path failed

Hi,

There is no way to run I/O jobs if you disconnect all cables from a storage. How did you know some I/O operations are going on that LUN?

Did you check with ioscan?,diskinfo?

Regards,
LIJEESH N G
Surajit
Occasional Visitor

Re: I/O is not affected due to both path failed

I have seen the out put of script and it is showing the job is script is running. I have tested same thing in other OS and whenever I disable the both path, it showing that script cannot write any data on the disk.
Turgay Cavdar
Honored Contributor

Re: I/O is not affected due to both path failed

It is clear that there is something wrong with the script. You can do your tests with dd command and see what happens.
Surajit
Occasional Visitor

Re: I/O is not affected due to both path failed

Hi,
I have checked my script, but not found any error. Whenver I have pullout the both fibre cable of primary and alternate path from the storage , then still script is running, but server become totaly hang. I cannot use any command on the server. But, whenever I connect the cables with the storage, server becomes normal. Please help me to solved this problem or are there any solutions for this problem
Torsten.
Acclaimed Contributor

Re: I/O is not affected due to both path failed

"... any solutions for this problem ..."

Don't pull the cables while your script is running ;-))

Seriously, what should someone suggest without knowing what your script does?
What do you suspect the system will do when all pathes are disconnected?

Hope this helps!
Regards
Torsten.

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Berd
Trusted Contributor

Re: I/O is not affected due to both path failed

Surajit,

Where are you pulling the cables ? I presume at the switch or storage end, as if you pulled from the server end you could potentially be impacting many filesystems.

It would be my guess, that you are not pulling cables from ports which refer back to your server. When you pull the cable do you seen any paths drop on the Unix server ?

Regards,
Berd
Mel Burslan
Honored Contributor

Re: I/O is not affected due to both path failed

as soon as you think both links were removed, even if only one of them gets removed, you should see some sort of complaint in your syslog file similar to PVlink failure or similar. Do you get these when you disconnect your SAN ? If not, you are not really disconnecting them.

Also, why disconnect from the storage side where you can achieve the same thing by disconnecting FO cables from your server's HBAs ? Any reason why you are removing connection from the the storage side ?
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UNIX because I majored in cryptology...