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khurni
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Contributor

VMware 5.1 VM with large RDM - options to get VM into Vcenter 6.0 system?

Hello,

Hopefully this is the right forum.

We have a VMware 5.1 Vcenter system.  We're in the process of migrating the VM's into a Vcenter 6.0 system at another data center (but we're not in charge of the other datacenter so we have to coordinate with another group).

Long story short:

We have one VM with a very large (5 TB) RDM.  Approx.3.3 TB of that disk is in use.  It's comprised of millions and millions of tiny files/directories (like 2kb or less).

The DataCenter folks say they can't import disks with RDM into Vcenter 6.

So our choices:

1)  Copy the data to a VMDK that's presented across the 10 GB data link to the new data center.  However, last time we copied the data (when it was a lot smaller) it took weeks to copy due to the small files (and if it burps along the way either copy dies, or it skips it and you have to pour over log files and manually copy the ones that didn't go or start copy all over again which still takes lots of time).  No our ideal method, if we can help it, since, unfortunately this would require massive downtime.

2)  We are aware that you can convert an RDM to VMDK, but it appears you need at least VMware 5.5 to do this.  Then copy the VMDK to the new data center and import into the 6.0 version.

We would like to do #2, but then that brings up other questions/options:

1)  Datacenter folks said they called VMware and VMware won't support converting RDM to VMDK since we're at version 5.1 and 5.1 isn't supported any longer.  OK, so we could upgrade our vcenter to 5.5/6.0

2)  Then datacenter folks said, "well if you upgrade to 5.5/6.0 it's really super complicated and hard and problematic with SSO".

3)  Then they said, well OK, if you do that, we don't know if the 3.5 TB VMDK file will copy over "well".  I'm not sure what process they are using currently. They have presented a LUN from their SAN (across the 10 GB fibre link) to our Vcenter (so our hosts and their hosts can see it).  I don't know if they're using Converter to get the VMDK and whatnot into their system.  Or if they're manually copying the VMDK (winscp or some other slow process) and then adding to inventory over there.

We were thinking:

Can we install (rather than upgrade, if it's so very very hard) a new Vcenter 5.5/6.0 system on our side (we have the hardware), and move/get the one VM from 5.1 over to our system and that would give us a good idea of how long it takes to do things?

One of our guys had questions:

Q1: can you add a vmx to a different version esxi?

Q2:  can you add a vmx to esxi if it has an rdm? (I'm guessing "no" based upon what the Data Center folks are telling us now, although not sure if that's true/correct or not)

Q3:  will we need to convert to physical rdm (yes, I'm pretty sure this is in the KB article somewhere that if you want to do a "live" convert RDM to VMDK you have to be in physical RDM mode or something)

Q4:  will converting rdm to vmdk take super long?

Q5:  will winscp be reliable for a multi TB vmdk?

Lots of questions, I know, we're just wanting the fastest way to get this done so we don't have a month or more of downtime like we did last time we had to copy the data from one disk to another via OS file copy.  Unfortunately we do not have the abilitiy to do a SAN to SAN copy as we are on a Dell/Compellent SAN and they're on an EMC Vmax or something SAN.

Thanks!

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khurni
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Contributor

So what was decided was to install a new 5.5 Vcenter.

Clone the existing VM (we'll detach the RDM first) into the new 5.5 Vcenter/host

Use the SAN to create a copy of the LUN/RDM

Attach the COPIED LUN to the cloned VM

And then we'll either:

1)  Convert the RDM to VMDK (target will be new SAN LUN)

or

2)  Use some partition tools like Gparted to copy the "shrunk" (via Windows 2012 R2 OS) partition to the target VMDK disk.  But have no idea how long that will take or how well it will work.

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khurni
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Due to unforseen circumstances we had to cancel our conversion, but we ran a test instead.

We used our SAN to create a copy of the 9 TB LUN/RDM.

We attached that copy to a test VM in Vcenter v5.5

We used a cold storage vmotion to convert the RDM to a thin-provisioned VMDK.

The data traversed a 10GB fibre link, but our old SAN is limited to 4 GB fibre channel (due to old Cisco switch), whilst new SAN has 10 GB links.  Basically we're limited to a 4 GB fibre channel speed.

The RDM only had 3.13 TB of used space (just an FYI).

The conversion took 17 hours.

In case anyone is wondering.

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