Virtual disk versus physical for WHS 2011 on HyperV

T

theinv

Limp Gawd
Joined
Apr 17, 2008
Messages
216
Hi,

For those of you that runs WHS (preferably WHS 2011) on Hyper V, do you use vhd or physical pass-through disk for storage? What is the advantage/disadvantage of each?

One drawback of vhd I can think of is you cannot view the content of the disk if you unplug it and connect it to a different machine because everything is in a ".vhd" file. Physical disk doesn't have this problem.
 
I think you're missing the point. He was talking about physically unplugging a drive, plugging it into another system, and pulling data off of it. You can't do that if the drive has a datastore (or whatever hyper-v calls them) with vhd file(s) on it. You can plug it into another hyper-v or win7, but that may not be possible or easy for the OP.
 
Wrong. I was simply pointing out that he was wrong in thinking that you could not get your data off if you use a VHD. So it bring us back the the original question. What is the best way to attach disks to WHS in Hyper-V.
 
fluke420 said:
Wrong. I was simply pointing out that he was wrong in thinking that you could not get your data off if you use a VHD. So it bring us back the the original question. What is the best way to attach disks to WHS in Hyper-V.
Click to expand...

I don't really want to get into an argument here. Just trying to point out that your suggestion may not always be possible or convenient.
 
danswartz said:
I think you're missing the point. He was talking about physically unplugging a drive, plugging it into another system, and pulling data off of it. You can't do that if the drive has a datastore (or whatever hyper-v calls them) with vhd file(s) on it. You can plug it into another hyper-v or win7, but that may not be possible or easy for the OP.
Click to expand...

Ok, so only hyperV VM can read the data. I think I am fine with that. This actually makes data more secure since not everyone can see the content of the disk unless they have hyperV.
 
benogil said:
You can go either way, there are good reasons for a VHD , given here - http://www.unproductivitydefined.com/2010/02/virtualizing-windows-home-server-on.html

Although the above was for WHS 1, the reasons for a VHD still hold.
Click to expand...

I just skimmed through it, but it looks like that article is just talking about using VHDs for the OS installation drive, not the storage pool. My impression was that the author was using passthrough disks for the pool drives.

I'm pretty sure I've seen other articles, though, that do discuss pros and cons of using VHDs for the storage pool (i.e. each pool drive has one big VHD on it taking up the whole disk). I can't find them at the moment, but a couple of things occur to me off the top of my head:

By using VHDs, the entire WHS system, including the storage pools, is "pulled in" to the virtual machine. This means you can take snapshots and use Windows Server Backup on the entire machine without losing synchronization between the pool and the tombstones (*very* important for WHS v1, probably not as big a deal for WHSv2, since it pretty much punts on the whole storage problem). In WHSv1, if you are just VHD'ing the OS drive, you might as well not bother with snapshots or even backups, since if the pool drives get out of sync with the snapshot, you are hosed anyway and will still need to reinstall the OS.

If you are sticking with WHSv1, you can cheat around the 4K sector hard drive problem by creating a VHD on the 4K sector disk, which will look like a 512-sector disk to the WHS VM (Hyper-V is based on Server 2008R2 which works fine with 4K disks).
 
theinv said:
For those of you that runs WHS (preferably WHS 2011) on Hyper V, do you use vhd or physical pass-through disk for storage? What is the advantage/disadvantage of each?.
Click to expand...

In my test setup at home, I ran WHS (v1) as VM with a smaller 80gb .vhd file for the O/S drive, and then did all of my storage disks as pass-through disks.

My reasoning was that WHS naturally tries to keep the landing drive clean, so all my data pretty much gets stored on the pass-through disks, which I have the pro of being able to easily plug into any system and read. Plus, I didn't see the need to add any overhead of wrapping everything in a VHD when I knew in advance I'd be using the full disk, and I could give full access directly to the VM. As an added bonus, due to the O/S being in a VHD, I could easily schedule time to make a copy of the 80gb .vhd and have a full back-up of the o/s drive if I were to ever lose that drive.

This setup worked very well for me, not sure how WHS 2011 will impact things. YMMV.
 
theinv said:
Hi,

For those of you that runs WHS (preferably WHS 2011) on Hyper V, do you use vhd or physical pass-through disk for storage? What is the advantage/disadvantage of each?

One drawback of vhd I can think of is you cannot view the content of the disk if you unplug it and connect it to a different machine because everything is in a ".vhd" file. Physical disk doesn't have this problem.
Click to expand...

So I have been using WHS and WHS 2011in Hyper-V for a long time and with a lot of instances. My thoughts on this are:

OS Disk: vhd is fine. Generally it does not get hit "that" hard where you cannot use a dynamically sizing disk. Putting Hyper-V on a RAID 1 array with a VHD on that array for WHS 2011 works well.

Data Disks: RAID 1/ 10/ 6 volumes passed through to WHS using the standard Hyper-V pass-through disk guide procedures.
 
pjkenned said:
So I have been using WHS and WHS 2011in Hyper-V for a long time and with a lot of instances. My thoughts on this are:

OS Disk: vhd is fine. Generally it does not get hit "that" hard where you cannot use a dynamically sizing disk. Putting Hyper-V on a RAID 1 array with a VHD on that array for WHS 2011 works well.

Data Disks: RAID 1/ 10/ 6 volumes passed through to WHS using the standard Hyper-V pass-through disk guide procedures.
Click to expand...

For OS disk, will running multiple VM on same disk impact performance? Should I use different disk for each VM?
 
theinv said:
For OS disk, will running multiple VM on same disk impact performance? Should I use different disk for each VM?
Click to expand...

It will depend on your setup. If you have a single disk, running multiple VM's off of it will definitely impact performance. If you have a a 10 disk raid10 setup with a single virtual disk presented to the O/S, you'd be fine with a few VM's.

I tried putting two VM's on an older single 500gb 7200prm SATA disk, results were moderate to poor. After splitting the two VM's on to separate disks, performance was great.
 
You must log in or register to reply here.
Back
Top