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7 Replies Last post: Feb 13, 2009 2:14 AM by vmiscsi1

iSCSI Target VM rescan posted: Feb 10, 2009 8:43 AM

vmiscsi1

3 posts since
Feb 10, 2009

Hi,

The setup is as follows: Using ESX 3.5 a Virtual Machine has been created on a the VMFS data store and takes up most of the disk space on the VMFS. An iSCSI target has been created on this Virtual Machine. The ESX iSCSI initiator was setup pointing to the iSCSI target on the Virtual Machine. A new VM was created on the iSCSI target.

When the ESX host machine is rebooted the iSCSI Target Virtual Machine boots up but the Virtual Machine installed on the iSCSI target does not appear in VI Client. Instead it is marked by the label 'Unknown (inaccessible)'. This makes sence because the Virtual Machine holding the iSCSI target, and therefore the Virtual Machine on the iSCSI target, cannot be referenced at boot up.

By rescanning the Storage Adapters in VI Client, the Virtual Machine installed on the iSCSI Target virtual machine magically appears and can be started as normal. My question is how can this rescan be done from the command line. I have tried the esxcfg-rescan command but believe the 'rescan' link in VI Client does a lot more than is immediately obvious.

Thanks.

Tags: iscsi, esx, vi, client

Re: iSCSI Target VM rescan

1. Feb 10, 2009 9:20 AM

in response to: vmiscsi1

weinstein5

7,077 posts since
Nov 19, 2005

esxcfg-rescan command should do it - I would also look at the shutdown/startup vm sequence

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Re: iSCSI Target VM rescan

2. Feb 10, 2009 11:18 AM

in response to: vmiscsi1

kjb007

5,624 posts since
Sep 18, 2006

the esxcfg-rescan command is really all that should be required. the rescan in the GUI rescans all of your HBA's at the same time, so you'll have to manually run esxcfg-rescan against all of your HBA's. Restarting the hostd (service mgmt-vmware restart) or restarting the management agents on ESXi should finish things up, but the rescan link does not do this.

-KjB

Re: iSCSI Target VM rescan

3. Feb 11, 2009 7:10 AM

in response to: kjb007

Texiwill

10,432 posts since
Jan 13, 2004

Hello,

Remember ESX does not like a VMFS that is 100% full. You need space for sundry files associated with the VM. Perhaps no more than 80-90% full. Too full and the VM may not boot.

Best regards,
Edward L. Haletky
VMware Communities User Moderator
====
Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
Blue Gears and SearchVMware Pro Blogs -- Top Virtualization Security Links -- Virtualization Security Round Table Podcast

Re: iSCSI Target VM rescan

4. Feb 11, 2009 8:39 AM

in response to: Texiwill

vmiscsi1

3 posts since
Feb 10, 2009

Thanks for the feedback. It is interesting that two posts suggest that the esxcfg-rescan is enough. I have done this and my observation is that once ESX has booted, and before running this command, the folder /vmfs/volumes contains dust the local data store. After the rescan command has been run the iSCSI data store appears in this volumes directory. The VI client still shows the virtual machine on the iSCSI target as inaccessible. Running the vmware-cmd getstate on the virtual machines .vmx file, which becomes visible after the rescan, returns the message "VMControl error -11: no such virtual machine". I have also read advice about restarting the management agents, This however restarts the iSCSI target virtual machine which puts everything back to step one.

Following Texiwill's post I have created the setup again, but this time the target iSCSI virtual machine fills only 50% of the local data store. The problem still persists.

Any further suggestions?

Re: iSCSI Target VM rescan

5. Feb 11, 2009 9:14 AM

in response to: vmiscsi1

Texiwill

10,432 posts since
Jan 13, 2004

Hello,

You may need to 'register' the VM first.. Does the output of vmware-cmd -l show the VM?

does

vmware-cmd -s unregister /full/path/to/VMX
vmware-cmd -s register /full/path/to/VMX

fix anything.

It sounds like the VM is not registered yet.

Best regards,
Edward L. Haletky
VMware Communities User Moderator
====
Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
Blue Gears and SearchVMware Pro Blogs -- Top Virtualization Security Links -- Virtualization Security Round Table Podcast

Re: iSCSI Target VM rescan

6. Feb 11, 2009 12:12 PM

in response to: vmiscsi1

kjb007

5,624 posts since
Sep 18, 2006

The problem as I see it, is that you have a vm that was created in a datastore which is being exported from another vm. When ESX comes up, it checks for its datastores, which it can't find, because the exporting vm is not yet up. Because the datastore is not yet available, the vm that lives on that datastore does not yet exist. After the vm is up and running, and the export is once again available, a rescan brings the datastore back, visible again to ESX. The vm that lives on the newly discovered datastore now needs to be visible again, which it may by itself, in a certain amount of time, after the datastore is visible.

Otherwise, the management agent restart should rush that re-discovery of the ghost vm. Restarting the management agents should not restart the virtual machine. What patch level are you running on your ESX host? Depending on your patch level, and vm auto-start setting, this may be the cause of the vm restart.

-KjB

Re: iSCSI Target VM rescan

7. Feb 13, 2009 2:14 AM

in response to: kjb007

vmiscsi1

3 posts since
Feb 10, 2009

I have now discovered the command that solves the problem. It is:

vimsh -ne hostsvc/storage/refresh

Running this command after 'esxcfg-rescan <vmhba##>' refreshes the VI client and all the VM's that are stored on the iSCSI target VM become visible and usable.

In responce to the remarks in a post further up about registering the VM's: I tried that a long time ago but if I registered, or done a getstate, etc on the VM, an error was returned stating that no such virtual machine exists, despite the .vmx and other files being navigatible through the directory structure.

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