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EmersonP
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How to Add a LUN with VMFS Format without formatting? in vSphere 5.1

Hi people, we need to mount a datastore that has been previously detached.

It suposed to be an option called: EnableResignature or >DisallowSnapshotLun but is not present at vSphere 5.1.

Can someone has a workarround for this? We just need to mount a datastore without format it!

We use vSphere 5.1 Ent.Plus Lic.

Please Help!

Regards

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MKguy
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You can always re-mount a detached datastore to a host if it's still aware that the datastore was just unmounted.

The EnableResignature or DisallowSnapshotLun options are only relevant if you present a new LUN with a VMFS volume to a host that already has a volume mounted with the same VMFS UUID (e.g. a SAN-side snapshot volume).

Since a few ESXi releases you don't even need to set the options manually beforehand. While adding the datastore in the vSphere Client it will just ask you what to do, whether to resignature the volume or not. Resignature just means it assigns another VMFS UUID and datastore name, that's all.

It does not reformat the LUN. So you can safely go ahead and mount the LUN.

Also see:

http://kb.vmware.com/kb/1011387

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MKguy
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You can always re-mount a detached datastore to a host if it's still aware that the datastore was just unmounted.

The EnableResignature or DisallowSnapshotLun options are only relevant if you present a new LUN with a VMFS volume to a host that already has a volume mounted with the same VMFS UUID (e.g. a SAN-side snapshot volume).

Since a few ESXi releases you don't even need to set the options manually beforehand. While adding the datastore in the vSphere Client it will just ask you what to do, whether to resignature the volume or not. Resignature just means it assigns another VMFS UUID and datastore name, that's all.

It does not reformat the LUN. So you can safely go ahead and mount the LUN.

Also see:

http://kb.vmware.com/kb/1011387

-- http://alpacapowered.wordpress.com
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EmersonP
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MKGuy, thanks four your reply.

Your right, our situation is that we re-attach a LUN that has been detached previously; that's why we need to add the "new" datastore without format, because it has a lot of virtual machines.

In the article you mentioned, is the procedure for adding unformatted (see Step 8):


But in our infrastructure this options are not available, that's the reason why I assumed we must modify the above value. (EnableResignature or >DisallowSnapshotLun)

ESXi 5.x

vSphere Client

  1. Log into the vSphere Client and select the server from the inventory panel.
  2. In the Configuration tab's Hardware panel, click Storage.
  3. Click Add Storage.
  4. Select the Disk/LUN storage type.
  5. Click Next.
  6. From the list of LUNs, select the LUN that has a datastore name displayed in the VMFS Label column.

    Note: The name present in the VMFS Label column indicates that the LUN is a copy that contains a copy of an existing VMFS datastore.

  7. Click Next.
  8. Under Mount Options, these options are displayed:


    • Keep Existing Signature: Persistently mount the LUN (for example, mount LUN across reboots)
    • Assign a New Signature: Resignature the LUN
    • Format the disk: Reformat the LUN

      Notes:
      • The Format the disk option deletes any existing data on the LUN.
      • Before attempting to resignature, make sure that there are no virtual machines running off that VMFS volume on any other host, as those virtual machines may become invalid in the vCenter Server inventory and will have to be registered again on their respective hosts.

  9. Select the desired option for your volume.
  10. In the Ready to Complete page, review the datastore configuration information.
  11. Click Finish.

Thanks in advance

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MKguy
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But in our infrastructure this options are not available, that's the reason why I assumed we must modify the above value. (EnableResignature or >DisallowSnapshotLun)

Are you sure this LUN is a valid, consistent VMFS volume? Did you present this LUN to any other system (like a Windows server) in the meantime? Windows loves to automount disks and destroying partition tables out of the blue simply by presenting a disk it can't recognize to it.

If this was a valid VMFS volume the host is able to read, then you would see the options quoted from the article.

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a_p_
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To use a previously detached LUN, you'll need to attach it again. See http://kb.vmware.com/kb/2004605 for details and commands.

André

EmersonP
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Well, we did some tests and found the answer. The procedure is only removed from the data store, move the LUN to other infrastructure, and the process of assembling data warehouse in the new infraestucture is automatic. That is the reason why no options appear:

"Keep Existing Signature: Persistently mount the LUN (for example, mount LUN across reboots)

Assign a New Signature: resignature the LUN

Format the disk: Reformat the LUN "


So I thank them both for their collaboration.


Regards!

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