How to mount BCV on Windows 2003 host manually?

Question

Hello,

Hopefully this will be easy one for local gurus here. I'm testing PowerSnap module for Symmetrix on Windows. So far we used this with UNIX and had no issues.

We made simple test configuration where we have:
host A acting as remote proxy (BCVR)
host B acting as local proxy (BCV) - application host

While configuration with BCVR works fine we have a bit of an issue with local setup. First we had issue where it failed with not being able to read signature for local BCV when it tried to mount it (funny enough, snap part worked fine). We thought there could be an issue with disk signature thus we rebooted host B as I found in KB that 2003 would correct signature upon reboot.

After that I did get a bit different picture where snap is done (establish/split), but now it fails with BCV being in incorrect stage. By doing multiple tests we saw that for some reason one of devices is not split, but rather established (and thus we get this error message). When doing symmir from command line everything works fine.

I'd like to take this step further when doing things from CLI - I wish to mount these BCVs (2) from CLI, but I have no knowledge of how to do that. Looking at KB I found command symntctl which doesn't exist anymore (at least with my SE) so I assume there should be a way of doing it with diskpart and mountvol somehow, but that's just in my theory. Can anyone give me a clue how to do it (and if there would be an example that would be great).

SKT2 · Answer

check the symevent for any failed disk (any hot spare invoke?).
In case of a STD failure(M1+M2) then the hotspare will get invoked and the BCV(which was in sync while the disk failure) compete for a mirror position especilally when you have a R2 already occupying the THIRD mirror position. In short BCV and hot spare fight for fourth mirror position and none of them finish syncing..!!

ble1 · Answer

... interesting enough we found that when running back for individual snapable volume that work. After that combination of two worked as well. It is really strange behaviour. We will try to reproduce it by adding 2 more BCVs.

ble1 · Answer

Everything is ok with symm devices. No errors there.

My further tests show that if I do a backup which includes snap of one disk then everything is ok (no matter which disk out of two snapable that I have).

If I do them at the same time PowerSnap module has certain issue where one device is left sync and not split and it fails. We are testing latest version of PS module (2.4SP1) and we are not happy with this - with 2.3SP1 this was not the case.

However, if someone could provide those steps for mounting BCVs manually on Windows host...

ble1 · Answer

I did, but with mountvol utility I do not see it reported (after rescan). I'm not sure if this could be related to the fact that default state is set to NR - set by PS module to protect BCVs made by module.

bodnarg · Answer

The symntctl command is part of the Timefinder Integration Module software package which is an optional software product. It basically provides some functionality that Windows did not (and still does not) fully offer out-of-the-box.

Specifically there are no tools (that I have found) for doing things like altering the disk signature which is what is required if you want to mount a cloned volume on the server with the source volume. If you are working on a different target server with the cloned disk you can use a combination of the diskpart and mountvol commands to manipulate the device by its physical drive identifier.

Once again with symntctl you can specify the drive by other identifiers such as symmetrix device ID which are not subject to change.

Short of this - if you want to do things from the command line talk to your local reps about getting a copy of TF/IM.

Hopefully a more savy Windows guru will prove me wrong...

dynamox · Answer

so after your BCV is split, have you tried to use diskpart and select rescan, after that you could see if mountvol -l will display the disk (it may not have a drive letter assigned to it but you could do that from a script)

ble1 · Answer

I'll just mention that to local EMC guru here... he will take it from there. I thought originally symntctl is part of symcli package (SE)... thanks for the info!

dynamox · Answer

take a look at dumpcfg from Microsoft. I have used it when i had issues with Windows changing disk signature for some unknown reason ..hence failing ms clusters that rely on disk signature for cluster physical resources. You can use this tool to write signature to disk in your case you would just write a random signature.

dynamox · Answer

oh yeah ..gotta make sure BCVs are split before you attempt any of these rescaning/import type of tasks. Cause you are trying to run backups from the BCV devices ?

ble1 · Answer

If the BCV is split but still NR (not ready) your
host won't be able to mount it.
You can manually make the device ready with "symdev
ready "

Yes, that's exactly why I was not able to see it with mountvol.

Since PowerSnap module is using SymAPI I assume it handles those signatures correctly (expcept when in hight debug mode like 9 when it has issues reading it sometimes) - it is mounting those volumes without much problems to the same application host.

MarcT2 · Answer

If the BCV is split but still NR (not ready) your host won't be able to mount it.
You can manually make the device ready with "symdev ready "

However, if you're presenting a BCV back to the original host, you'll then have issues with duplicate disk signatures. "symntctl" (part of the TimeFinder Integration Module as mentioned above) provides CLI functions to manipulate the disk signatures.

If you're presenting the BCV back to a different host, then rescan for devices & assign drive letter should mount the disk.

In Win2K disk management conducted over Terminal Services / Remote Desktop would not work reliably. The hardware is virtualised when you first connect and new devices discovered during the session don't show up at all. Usually disconnecting & re-connecting will would make them appear. You can run into similar issues in W2k3, so I think it's still preferable to perform disk management on the physical machine itself.

Just my 2p (that's two new pence...)
Marc

ble1 · Answer

dumpcfg sounds nice - I never heard of it before. Anyway, in the meantime I found what was going on. It seems as if PowerSnap module is running in hgh debug mode (something that I always do for first test backups) it may have issues reading disk signature. Obviously this is not always the case as I was was able to make it run keeping the same debug level, but this seems to be known issue for PowerSnap module.

Symmetrix

How to mount BCV on Windows 2003 host manually?

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