infuseweb
Contributor
Contributor

How to properly resignature a LUN?

I'm testing VM recovery from tape backup to a LUN on my SAN. I have several ESX hosts in a DRS cluster.

I can restore the LUN from tape and recover the data with no problem. But as I understand it, in order to restore the VM, I have to resignature the LUN. I'm getting stuck figuring out the right steps to do this so that the LUN reappears under the original name and available to all the ESX hosts in the cluster. Can anyone provide any guidance on the best way to do this process?

For example, do I have to enable resignaturing on every ESX host in the cluster or just one? And at what point do I disable resignaturing again?

Tony

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ncentech
Enthusiast
Enthusiast

Hello, first of all I don't know if you still need the help but maybe some other people will benefit from this. When you restore a LUN from tape backup you have different options depending on what you want to accomplished. If you want the restored LUN permanently available or if you want it just temporarily so you can pull data out.

If you want your restored LUN permanently you will use the resignature option and make sure to do it presicesly or else you might run into issue. Take the following steps

1. unpresent or make sure the failed LUN is no longer visible to your ESX hosts.

2. depending on your SAN (I use netapp) present it to your hosts and give it a different LUN ID.

4. Go to Advance settings and go to the LVM section and change the seting on enable resignature from 0 to 1(Do it only from ONE esx host.)

5. Rescan one of the ESX host hbas and make sure the new LUN is visible.

6. Once you are able to see the new LUN it will also create a new data store automatically.

7. Once you are able to see the new Data Store witht he associated LUN go back to the Advance options and change the settings back to 0 for enable resignature.

8. It is very important to do step 7 becasue if you don't the next time you rescan the hbas it will give it a different GUID to the LUN and it will start to get confusing.

9. After that you go ahed and rescan the HBAs on the rest of the ESX host and they will be able to see the new DataStore with the associated LUN.

If you want to just browse the LUN and get vmdk files out then you will use the enable snapshot option in the advance section of the ESX host. You will have to do the following

1. change enable snapshot from 1 to 0

2. rescan one of the ESX hosts HBAs and make sure the new Datastore is present with the name of snap.00000xxx etc...

3. keep the setting enabled for the lenght of time you would want to keep it and browse it until you have gotten all of the information out.

4. Once you are done, change the setting back to default and the snapshot will no longer be visible

5. unpresent it from the SAN, rescan the ESX host you used to pull the data out and you should be done.

I hope this helps anybody. Regards,

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