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mreavis
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Getting around 2TB VMDK limit for file servers

Post by mreavis » Dec 18, 2012 6:38 pm

I've seen quite a few posts around this subject, but there doesn't seem to be a clear "best practice" method. I have a file server with 6 volumes that are shared out. These volumes are connected inside the VM using the MS iSCSI initiator, so obviously they aren't being backed up by Veeam. Most of these volumes are over 2TB, so they can't be put on a single VMDK. I know that I can create multiple VMDKs per volume and combine them in Windows (2008R2), but I'm hesitant to do this because of issues we've had in the past with dynamic disks. I've never used RDMs, but if I understand correctly I'd have to use the vRDM instead of the pRDM, which still has the 2TB limit. My other option is to leave it as is and replicate between SAN volumes, but that will make it more difficult to manage and archive to tape. Any other ideas/options? Is there anything I'm overlooking?

chrisdearden
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Re: Getting around 2TB VMDK limit for file servers

Post by chrisdearden » Dec 18, 2012 6:59 pm

Thats pretty much it at the moment - the other option would be to use mount points for your multiple 2TB volumes , but not everyones data is going to fit that way.

Other than that you will need to wait for Vmware to get their act together , or host that file server with Hyper V ;)

mreavis
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Re: Getting around 2TB VMDK limit for file servers

Post by mreavis » Dec 18, 2012 7:20 pm

We actually are licensed for Hyper-V as well, but haven't used it at all. I may try testing it out to see pros/cons vs. VMware. Do they have something comparable to vMotion/Storage vMotion for Hyper-V yet? Also, does Hyper-V handle RAM management of VMs better than VMware? Once we started building our VMs as 2008 boxes, the OS grabs way more RAM than it's using from the host which sets off alarms in vSphere.

Thanks!

chrisdearden
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Re: Getting around 2TB VMDK limit for file servers

Post by chrisdearden » Dec 18, 2012 7:51 pm

Its worth a try - especially with Server 2012 - Live migration & storage migration are available ( even with the "free" version ). I'm not sure if the Microsoft approach to RAM is nessesarily "better" as it doesn't attempt to do TPS etc , but the Dynamic memory feature seems to work pretty well in my test environment. It certainly worth a try - even if it is as a point solution for those large scale VM's

veremin
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Re: Getting around 2TB VMDK limit for file servers

Post by veremin » Dec 18, 2012 7:57 pm

mreavis wrote:Do they have something comparable to vMotion/Storage vMotion for Hyper-V yet?
Yep, in the Hyper-V 3 (included in Windows Server 2012) there is a completely new functionality called Live Migration Without Shared Storage (also known as “Shared Nothing Live Migration”). It enables you to migrate virtual machines and their associated storage between servers running Hyper-V. This kind of live migration uses only an Ethernet connection.

With this network connection, you can move a VM between Hyper-V hosts, including moving the VM's virtual hard disks (VHDs), memory content, processor, and device state with no downtime to the VM.

More information can be found on MS specialized resources.

Hope this helps.
Thanks.

mreavis
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Re: Getting around 2TB VMDK limit for file servers

Post by mreavis » Dec 18, 2012 8:12 pm

I was actually planning to build a new 2012 server soon to test out some of the new storage features in the OS, so I will enable Hyper-V to test that as well.

Thanks guys!

Vitaliy S.
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Re: Getting around 2TB VMDK limit for file servers

Post by Vitaliy S. » Dec 18, 2012 10:25 pm 1 person likes this post

mreavis wrote:I was actually planning to build a new 2012 server soon to test out some of the new storage features in the OS, so I will enable Hyper-V to test that as well.
My test lab's SQL Server as well as the vCenter Server itself are running as VMs on a Hyper-V host, so far so good... ;)

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