lun migration

sara2000
sara2000 used Ask the Experts™
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Have few physical servers attached to equallogic storage's LUN via guest os initiator (RAW lun) and want to migrate this lun to EMC vnx.
Many of you must have done this in your environment,  What is the best way to do this?
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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
you cannot easily move/migrate RAW LUNs between SAN vendors, so it comes down to a basic copy from LUN A to LUN B.

so present LUN A and LUN B to the same physical server and then use you favourite clone disk tool to copy the volume or partition.

robocopy can do the same sync or mirror operation until cutover.
SHBSystems Consultant
Commented:
For the same set up, I use EMC Open migrator. This is an online storage (block) level migration tool.

Author

Commented:
I was told that robocopy is not an ideal for the data which we have on that LUNs.
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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
why? what was the reason.

clone it then.
I can think of three possible reasons not to use Robocopy:

1. The LUN contains a large, active database. Robocopy will work if you shut down the activity for the duration of the copy but, even with shadow copies, it's not going to be easy to sync the two LUNs if there's ongoing activity.

2. The LUN is not a Windows file system (i.e. not NTFS or some version of FAT). Yep, Robocopy won't help with that.

3. The LUN is NTFS, but you want to preserve some extra aspect of the layout or shadow copies or peculiar junction points that Robocopy will not handle as you wish.

All of these are situations where shutting down the VM and using a suitable cloning tool will do what you want. If shutting down the VM is not an option, you're going to need assistance from the workload application(s) to manage the migration. For instance, you can move Exchange mailboxes while Exchange is up, but you may need to temporarily adjust the logging behavior so you don't end up consuming all of your space.

Author

Commented:
May be i did not give enough info, this is not VMs, they are physical servers attached to equallogic lun using microsoft iscsi initiator. SQL applications.
No, you said physical server alright. I just inserted the idea of VMs because of the VMware tag on the question.

I think my advice remains the same for physical servers.

So the choice is between a block-for-block clone of the LUN...several tools will do that...or a file-system aware copy that would not copy parts of the LUN that don't contain data, with Robocopy being an example. The block-for-block copy might still be faster, despite the extra copying, because it boils down to sequential read from one LUN and sequential write to the other.

I'm not aware of a way to do this "live", as might be possible if you were migrating LUNs served by compatible storage systems.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
Depends whether you can turn off the SQL Servers!

CLONE Tool, or Migrate the SQL applications correctly.

Author

Commented:
I will try and let you know how it went.

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