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Weird LVM behavior

 
Mike Smith_2
Advisor

Re: Weird LVM behavior

I can't say vgscan and ioscan get no response from the EMC, as the gatekeepers show up every time.

I can't block bus scans on the EMC, nor would that explain the gatekeepers showing up, but not the data volumes.

VGdisplay and pvdisplay do come up normal, including their alternate links.

I'll run it by EMC and see what they say.
Tim Malnati
Honored Contributor

Re: Weird LVM behavior

I was referring to the 12 partitions thinking in terms of data partitions from the EMC side; the same thing that you called 12 data volumes. When I read through your inq output this became obvious and it's also obvious that you have six gatekeepers.

I seem to recall that gatekeepers are not mission critical to the continued operation of the data volumes. I was told once that there was no requirement to have gatekeepers redundantly defined on both scsi buses (although preferred). If a scsi bus were to be lost during operation, alternate links would pick up, but there was no specific need for a gatekeeper at this point. I'm working from memory here, so this could be very wrong either on my part or the EMC rep who told me. There is a possibility that there may be something wrong with ioscan, but I'm certainly not convinced that this process is at fault where it is stable in broad terms. But I'm also thinking that the gatekeepers may have something to do with this where I think they are part of the mix that reports what devices are there to the ioscan process. Or in other words, is it possible that one or more of the gatekeepers is corrupted somehow?

Sorry for missing the CDROM thing. It went right over my head at the time. As I said before, I'm no EMC expert. My target is your problem, but gaining some additional knowledge along the way is a big reason I participate in the forums.
Mike Smith_2
Advisor

Re: Weird LVM behavior

You're right, gatekeepers need not be redundant, but it could potentially help if they are.

There are 12 volumes @4.3GB apiece for ~50GB.

I know 4.3GB volumes on an EMC is considered excessively granular (at least, it is to me), but I had a limited amount of disks we could purchase at the time, and a broad range to apply them to.
Wodisch
Honored Contributor

Re: Weird LVM behavior

Hi Mike,
while "ioscan" reports not all drives/targets, does "diskinfo" work on those
"missing devices"? That could be a clue, at least...
What is the timeout (pvdisplay) for those drives?
...still looking for more hints what is going on...
Wodisch

Re: Weird LVM behavior

Couple of things I'd check...

Does 'ioscan -kfC disk' show the same as 'ioscan -fC disk' - i.e. does what the kernel think is there match with what a physical scan of the bus suggests is there ?

You say all the device files are present in /dev/dsk what does the output of 'lssf /dev/dsk/*' return?

Is EMCs Volume Logix software installed on this, or any other machine attached to the saem EMC rig - Volume Logix controls which hosts can see certain devices in a rig, I've never come across any problems with it but...

Have EMC actually dialled into the rig and checked everything out?



I am an HPE Employee
Accept or Kudo
Mike Smith_2
Advisor

Re: Weird LVM behavior

Diskinfo results: (Character filename came from INQ output.)

diskinfo -v /dev/rdsk/c4t0d1
io_search failed: No match found.

ioscan -kfC disk output matches ioscan -fC disk output.

lssf output:

lssf /dev/dsk/c4t0d1
sdisk card instance 4 SCSI target 0 SCSI LUN 1 section 0 at address ??? /dev/dsk/c4t0d1
Abbott Vascular
Occasional Advisor

Re: Weird LVM behavior

have you tried an insf -e? This sometimes works when an ioscan -fn C disk doesn't return the expected volumes when dealing with EMC.
IE Admins
Advisor

Re: Weird LVM behavior

Hi,

I think that you are seeing a common problem with HPUX & EMC - something which I have seen before, but why you see the gatekeepers is strange.
I don't feel that you have a problem with the EMC per see. The number of gatekeepers is OK. In fact you need gatekeepers to run EMC software such as SymmManager etc.

The solution I have used in the past is as follows.

DON'T REMOVE YOUR BOOT/ROOT device files!!

I have done the following online several times with large Oracle DB's and haven't run into any problems. However you should check out the solution before you proceed.

1. Remove both /dev/dsk & dev/rdsk device files with:
rmsf -H your_hardware_path - abbreviate your hardware path so that you remove all device files on the path.

2. check that the device files you expected to remove have in fact gone from both /dev/dsk & /dev/rdsk.

3. Re-Create the device files
insf -e -H your_hardware_path (as above)

4. Look at your hardware again
ioscan -fC disk (you won't see the EMC)

5. Re-Create the device files AGAIN
insf -e -H your_hardware_path

6. Look at your hardware again!!
ioscan -fC disk - The EMC devices SHOULD NOW be there!!

I hope your problem is solved.

Regards
Mike Smith_2
Advisor

Re: Weird LVM behavior

Not meaning to sound like a bonehead, but what do you mean by 'abbreviate your hardware path so that you remove all device files on the path.'?

For example, the missing devices have HW paths of 8/8.0.1 thru 8/8.12.1 with the alternate link being 10/8.0.1 thru 10/8.12.1.
IE Admins
Advisor

Re: Weird LVM behavior

Mike,

Sorry for any confusion. The EMC layout you have is quite simple as you only have one logical disk per target. So if you wanted to remove a "single" device driver eg c0t15d0 the hardware path for instance would be 8/8.15.0

To remove "all" gatekeepers of c0t15d0-5 would be a hardware path of 8/8.15.

To remove "all" devices on the controller say c0 would be a hardware path of 8/8

So by limiting the hardware path allows for controlled removal of one, some or all device files attached at a controller in a single pass.

To get the hang of it pick a single logical say c0t0d1 and follow the instructions and see what happens. If this is successful the do the lot at one time.

Should you need advice my email is weaver@integral.com.au

Good luck.