jatdesi
Contributor
Contributor

vcbMounter error: Cannot access SAN/iSCSI LUN backing this virtual disk

Hi - I am trying to backup a single VM using vcbmounter (CLI mode). The VCB itself runs in a W2k3 VM. This VM sits on an ESX 3.5 server. All VMs on this ESX box are stored on an iSCSI LUN. The command I run is:

vcbmounter -h esxhost/VC_host -u user -p passwd -a ipaddr:VM_FQDN -r e:\backups\vmbkp -t fullvm -m san

Drive E:\ is an additional disk on the VCB VM and is pointing to the local storage on the ESX box. I even tried adding drive E:\ from the iSCSI LUN (where all VMs are stored). The backup process backs up all the log files, then errors out with the above error, and deletes the vmbkp folder on e:\. Drive E:\ has enough space to hold the backup of the VM.

Any help is appreciated.

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5 Replies
dmaster
VMware Employee
VMware Employee

Do you have enough diskspace left on your e-drive ? and is this e-drive shown as a local disk drive on the VCB server ?

Do you have enough permissions to write to the e-drive ?

Did you try using the Virtual Center server and specified the ip-adress instead of VM_FQDN ?

Do you get the same error when you try backing up over the LAN (instead of -m san you should use -m nbd) ?

jatdesi
Contributor
Contributor

The VM I am tying to backup has a 35GB drive and E:\ is a 50GB drive.

I am looged in as local admin on the VCB and running the vcbmounter in the same user context.

Yes, I tried using the VC server and also tried using the IP address (same result).

Have NOT used -m nbd. Will try it right now. Also, I was under the impression that since the VMs lie on an iSCSI LUN, the san mode will completely offload the processing from the ESX host, whereas, nbd would make the ESX pass the data to VCB.

Update:

It works when the option -m nbd is used. Also, I tested VCB installed on a physical server by itself. In this case, the -m san option works. Seems like if VCB is a VM, then -m nbd is to be used (even with iSCSI). Aother thing I noticed is that when making a backup and pointing vcbmounter to the VC server, I can see that snapshot creation/release events are logged. But when pointing vcbmounter to the ESX server, the backup goes through fine but I do not see any events for snapshot creation/release. Is this expected?

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kjb007
Immortal
Immortal

Have you verified that you can see the vm's disk through an iSCSI initiator. Without having access to the ESX LUN directly, you can not use SAN mode, which is why nbd is working, and the san mode is not. If you can mount the LUN using iSCSI initiator, then the san mode should work as well.

-KjB.

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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jatdesi
Contributor
Contributor

KjB - Thanks for your suggestion. I did not try what you are asking, but will do it today. I thought since the VCB was a VM on the same LUN where all the other VMs reside (and I could run vcbvmname and see all VMs), the option -m san would work. But, I'll install the MS iSCSI software initiator on the VCB vm and try the -m san option.

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Ashwin89
Contributor
Contributor

Hi.

How should I identify which mode I have to used for vcbmounter?

I need programatic way to find the storage type on ESX server.

any pointers?

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