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Virtualization Questions

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  • Virtualization Questions

    Hello Folks:

    I am in the process of deciding migrating a heavily used file server to a brand new server. I am trying to decide whether this particular server would be a good candidate for virtualization and I am realizing that there are many specifics about the subject that I can't answer.

    Some details first. I am planning on using vmware ESX server and the main operation system would be windows 2008 R2. This would all be running on a dell PowerEdge 2970, Quad Core AMD Opteron 2372HE 2.1GHz with 16Gbs of RAM & 1Gb ethernet cards.

    It would obviously seem to me that the server it self is a bit of an overkill in processor and memory resources just for running a file server and this is part of the reason I am considering using ESX as I may later on take advantage of some of the other resources by installing other O/Ss.

    Some of my questions are:

    1- This file server would get very high I/O requests. Previously (about 3 years ago) I had heard that servers with this high I/O demands were not good candidates for virtualization. I am not sure whether that was the case or not but I just want to confirm that this isn't something that could potentially be an issue. I was reading this article "350,000 I/O operations per Second, One vSphere Host" and it looked quite impressive so this may not be an issue but I figured I'd check.

    2- Storage is one of the main reasons that I am moving from the old server. The current infrastructure is not flexible enough to allow me to resize volumes. What I would like to do eventually is to be able to set up a RAID which will be used by the hypervisor to assign storage to the Guest O/S. If I run out of storage (or close to it) then I would like to be able to assign more space to existing "datastores" in my windows 2K8 drive and resize those partitions within the O/S. I suppose my question is how does ESX handle working with firmware RAIDs?

    3 - Backups. I would certainly design a backup plan for data within the O/S of the file server. However, for disaster recovery scenarios does ESX have a way to backup running VMs? Is this what VM snapshots would be used for? if I were to take a snapshot today and say I got infected with a virus that destroys half of my data tomorrow then would I be able to confidently restore using the previously taken snapshot?

    I appreciate all of you help on this. Should there be any literature anyone feels would compliment responses to these questions I'd be greatfull if you could reference it. Thanks again!

  • #2
    Re: Virtualization Questions

    as a starting point - go out and validate whether 2008 R2 is fully supported using ESX ! someone on the vmware forums the other day told me it wasn't...

    ESX won't handle working wit the RAID firmware. Basically, whnat you do is build a logical volume (say, RAID5) using your PERC6 firmware.
    The ESX Server then sees this volume, and formats it as a 1Terabyte VMFS volume, that can only be seen and understood by ESX.
    On that 1TB vmfs volume, you then create a 'virtual disk file' or vmdk file, for your virtual machine.
    this could be the full 1TB, or it could only be 500 GB.
    Once you start running out of space on your 500GB, you can create a new 'vmdk' file, and add it to the virtual host.
    Once you run out of the 1TB datastore, you can add more disks, and using OpenManager, you could create a new dataastore, potentially without taking the machine down.
    You would need to restart the virtual guest every time you added a new virtual disk however..

    to backup running machines, vmwware has a process called 'snapshot'. There are several COTS programs that will assist - my favourite is Vizioncore vRanger.
    Basically what it does is take a 'snapshot' of the machine which creates a new file that all changes are written to while the backup runs. The snapshot frees up the actual vmdk files, which are written to an archive somewhere.
    THen once the backup is finished, it deletes the snapshot - merging the changes into the existing file. (This is a fairly simplified solution of how it works)

    Snapshots are included as standard with esx and esxi, vRanger costs. There is a free script solution called VISBU.

    there;s no way you'd get that 350K IOPS with just direct internal storage.. you need to dive into the fibre channel realm.. and that's expensive
    Last edited by tehcamel; 25th October 2009, 00:47.
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