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How do you do....it? Thread, Virtualisation tutorial in Technical; Originally Posted by Skinny I guess the things I don't understand or want more info on are: I'm not sure ...
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    tmcd35's Avatar
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    Quote Originally Posted by Skinny View Post
    I guess the things I don't understand or want more info on are: I'm not sure about hardware requirements to run it without it seeming sluggish. I'm also concerned about putting all the eggs into one basket so to speak, because the whole OS and everything on it is stored as a single file what if the underlying system went t1ts up? If I had multiple virtual machines running I'd lose them all.
    I've found the trick with virtualisation is to just treat each VM as if it was it's own physical machine. If you were to go out and purchase a physical server to do that job what spec it would be? Then that is the spec the VM should be. How meny VM's do you want to run on the host? Tot up the total spec's of all the VM's you want to run on the host and you get an idea of processor power and memory requirements for the host.

    It's cheaper buying one physical server with 8-cores and 16Gb ram to run 4 VM's than it is to buy four physical servers each with 2-cores and 4Gb Ram.

    There's a little more to it than that - %age of cpu time each VM is idle (how much cpu power is really needed), and which VM archtecture you use (VMware is better than Hyper-V at memory allocation) - but essentially that's it.

    As for eggs in one basket. Thats the old risk assessment/cost-benefit trade off. Redundancy plays a part. Two host servers in stead of one, each able to take up the slack if the other fails. SANS/NAS storage so multiple hosts can get access to all the VM images.

    Then you look at redundacy is the SAN/NAS environement as a single point of failure and Disaster Recovery plans. How you back up the VM's, how often you do it and how easy it is to restore those backups.
    Last edited by tmcd35; 21st February 2010 at 05:05 PM.

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    Quote Originally Posted by Skinny View Post
    1 putting all the eggs into one basket
    2If I had multiple virtual machines running I'd lose them all.

    3I've also thought about using it on client machines... ghost image per build, I'm trying to get autoinstalls or find ways of rolling out the software automatically
    1 Yes you are and thats why people tend to go for virtual pools and (clustered) SANs when doing that sort of thing.

    2. Yes they'll all die, but the beuty of VMs is they only need a specific underlieing host OS, rather than specific hardware which could potentially be impossible to find if your server is old. You simply build a new host server and import the backed up VMs. Over 2 days i managed to import 14 VMs, id hate to imagine how much of a PITA it would have been with physical servers!

    3. Decktop VMs are a bad idea unless you are willing to go the whole hog and go with the likes of xenapp. Your OS and app depolyment is a totally seperate issue to virtualisation imo. Have a look at Autoimage (roguespears)and driverpacks.net for OS deployment. And building MSIs for apps.

    I have XP as a universal image for any and all PCs. And MSIs and scripts for all our software. Just netboot a PC, type in my password, give it a name and put it in a group. Come back an hour or so later and its ready to go.

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    Skinny's Avatar
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    Good answers, confirming what I suspected. I work alone most of the time and sometimes doubt my own figuring so it's good to see what others are doing. Cheers.

    I haven't seen autoimage i'll look into it, I'm just messing around with installrite at the minute and ghostAI plus autoIT.
    Quote Originally Posted by j17sparky View Post
    I have XP as a universal image for any and all PCs. And MSIs and scripts for all our software. Just netboot a PC, type in my password, give it a name and put it in a group. Come back an hour or so later and its ready to go.
    That's where I want to be. Unfortunately there is so much varying software in the schools and most of it is designed for Win95 (no MSI's) and the like that it will take me ages to sort through plus I only get 3 hours per fortnight in each school so it's a slooooow process.

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    synaesthesia's Avatar
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    Yeah there's cost to Acronis - I've been told things like Clonezilla might actually be able to do the same thing but I've yet to experiment

    You can decrease some of the problem areas with VM's by allocating physical hardware too - i.e. a separate HDD or even array of HDD's for each VM if you really wanted to - true they'll still be dependant on the host OS but there's many ways of setting it up to complete the tasks you need.

    Are they usable/feasible in a production environment? Too right - you can get a bloody good server together, make use of things like ESX/GSX (can't remember which is which tbh!) and run 2 or more virtual servers side by side - allocate separate drives and even processors/threads to each one - I've only seen this being done once a while ago for a top flight motorsports team and I was amazed at the level of performance they were getting out of it - and the amount of hard work it was doing. Normally they'd have needed a rack full of machines to get the best from it however for portability reasons this was a real cost saver without the lack of performance.

    I've often wondered about smaller site schools using them - for instance an MIS server and curriculum server running on the same hardware, virtualised. Could be quite cost effective.

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    Quote Originally Posted by synaesthesia View Post

    So, use Acronis True Image to take a full image of the server, pop it on a USB drive. Make a VM, and restore the image to said VM using Universal Restore (similar to symantec BESR if you've not used it - similar & better IMO, using that can half the migration time from one server to another if you need to do it like that).
    You could just 'convert' the server to a VM too.

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    Quote Originally Posted by john View Post
    I would agree with what you have done, just looking at doing the exact same thing, well different Oracle servers as the X4150s seem to have gone now (guess they have gone EOL). But I will be using my 7110 for the storage of the VMs.

    Out of interest what spec 4150s do you have? I was thinking of using 4 hosts but if you used 2 I may get away with less but a slightly higher spec in them perhaps?



    Our 2 x4150's are 2 x Intel E5450 3.0Ghz quad-core Xeons with 20 gb Ram. I've got 4 VM's on each. 2 busy fileservers, 2 DC's, a web/print/wsus server, a Citrix gateway server and a Citrix Xenapp box and another couple doing bits and bobs. The x4150s seem to cope really well i've never seen the CPU get over 30% so far. The SAN seems to cope well also i've got 3 NICs in an LACP bond for iSCSI and although it gets busy i've never seen it struggle to cope.

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    Quote Originally Posted by tmcd35 View Post
    ...
    There's a little more to it than that - %age of cpu time each VM is idle (how much cpu power is really needed), and which VM archtecture you use (VMware is better than Hyper-V at memory allocation) - but essentially that's it.
    ...
    This is one of the key benefits of virtualisation, if you use correctly configured software, you can have 4 VMs each with 4GB RAM but only have 12GB RAM on the physical hardware. but you get the idea. Ditto CPU usage. The Virtualisation software is essentially a powerful resource handler.

    Not only do you get cost savings by only buying one server to host many, but in theory the spec doesn't have to be the sum of the parts you would need in a physical environment. Factor in the ability to buy one support contract over 3, possibly a better level, and it makes real sense to go down this route.

    As for other issues. VMWare has a converter that lets you freely convert between different versions / host systems including non-VMWare files. Also, you can do a physical to virtual conversion so you don't necessarily need to use the backup/restore method.

    I clone machines really quickly by just copying the file to another host and then open it up. So that potential single point of failure is actually remarkably easy to restore. Now if it's on a SAN in a raid config, that gives you fault tolerance.

    We are planning our deployment now, for a Sharepoint setup and i plan to use at least 2 Blade servers, rigged up so that 1 will take up the slack if i ever need to reboot the other (or the guests it is hosting). Hopefully we'll soon add a couple more blades to help ease the load. The blades are dual quad-core Xeons 3ish GHz, 12GB RAM per blade. Each has one dedicated drive and the rest is shared storage. Initially thinking of 3 VMs per blade, but if it goes well more....

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    tmcd35's Avatar
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    Quote Originally Posted by vikpaw View Post
    This is one of the key benefits of virtualisation, if you use correctly configured software, you can have 4 VMs each with 4GB RAM but only have 12GB RAM on the physical hardware. but you get the idea.
    I was avoiding that example It's one of the key differences between VMWare and Hyper-V. With Hyper-V if you want 4Gb of ram for 4VM's you'll need atleast 17Gb on the host - 4Gb for each VM + some RAM for the host.

    VMWare allows you to over commit the memory. It does this in a number of ways - firstly by realising that it's rare that any one VM, let alone all 4 (in this example) will max out thier 4Gb allocation. It also monitors what's being run in the VM's. All four running the exact same version of Windows? not a problem, only one copy of the various library files, etc needs to be loaded into ram for all four copies to share.

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    Quote Originally Posted by tmcd35 View Post
    I was avoiding that example It's one of the key differences between VMWare and Hyper-V. With Hyper-V if you want 4Gb of ram for 4VM's you'll need atleast 17Gb on the host - 4Gb for each VM + some RAM for the host.

    VMWare allows you to over commit the memory. It does this in a number of ways - firstly by realising that it's rare that any one VM, let alone all 4 (in this example) will max out thier 4Gb allocation. It also monitors what's being run in the VM's. All four running the exact same version of Windows? not a problem, only one copy of the various library files, etc needs to be loaded into ram for all four copies to share.
    That's a useful Heads UP, i'm evaluating Hyper-V at the moment. I was under the impression that the stand-alone, bare metal version didn't have any major overhead....?

    I also, wasn't aware that it wont do smart memory management. I assumed they all do that. Luckily our blades are RAM rich, but i'm starting to rethink and go down the ESXi route, just need to fine a decent GUI based manager. Ideally a free one...i think there's a thread on that somewhere.

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    tmcd35's Avatar
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    You need to remember Hyper-V isn't quiet as bare metal as ESX. It's a little more like Xen on Linux. It needs a primary copy of Windows to run with. So you have the overheads associated with running an additional copy of Windows. Maybe less than the 1Gb I quoted above - maybe 256mb - but essentially you need ram for all your VM's and the host.

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    There's a good Hyper-V article here.

    Resource Allocation in Hyper-V (Part 1)

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    Quote Originally Posted by tmcd35 View Post
    You need to remember Hyper-V isn't quiet as bare metal as ESX. It's a little more like Xen on Linux. It needs a primary copy of Windows to run with. So you have the overheads associated with running an additional copy of Windows. Maybe less than the 1Gb I quoted above - maybe 256mb - but essentially you need ram for all your VM's and the host.
    Quote Originally Posted by cookie_monster View Post
    There's a good Hyper-V article here.

    Resource Allocation in Hyper-V (Part 1)
    @tmcd35 - does that include the new standalone version? i'm liking it less and less now.

    i think the referenced article might be running on an older version where you still have to have a core SVR install.

    i was under the impression the standalone is just bare metal and runs from a command prompt, but am happy to be corrected as i'm not happy about using a Microsoft OS as a host for other machines just because of all the patching that is required. i haven't had time to investigate more yet as other projects taking precedence.

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    Quote Originally Posted by vikpaw View Post
    @tmcd35 - does that include the new standalone version? i'm liking it less and less now.

    i think the referenced article might be running on an older version where you still have to have a core SVR install.

    i was under the impression the standalone is just bare metal and runs from a command prompt, but am happy to be corrected as i'm not happy about using a Microsoft OS as a host for other machines just because of all the patching that is required. i haven't had time to investigate more yet as other projects taking precedence.


    It's worth noting that Hyper-V isn't Windows based and is a purpose built OS from the ground up. It's only required one security patch so far.

    Microsoft Hyper-V gets its first security patch | Virtualization - InfoWorld

    http://www.microsoft.com/technet/sec.../MS10-010.mspx

    I'm not supporting Hyper-V in any way (I'm a Xenserver user) just pointing out the differences.
    Last edited by cookie_monster; 22nd February 2010 at 12:43 PM.

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    Quote Originally Posted by vikpaw View Post
    That's a useful Heads UP, i'm evaluating Hyper-V at the moment. I was under the impression that the stand-alone, bare metal version didn't have any major overhead....?

    I also, wasn't aware that it wont do smart memory management. I assumed they all do that. Luckily our blades are RAM rich, but i'm starting to rethink and go down the ESXi route, just need to fine a decent GUI based manager. Ideally a free one...i think there's a thread on that somewhere.
    XenServer is also unable to overcommit memory at the moment. The next release (previews are in March I believe) has it, but until then I think VMWare are the only "enterprise" solutions that have memory overcommit.

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    Quote Originally Posted by cookie_monster View Post
    It's worth noting that Hyper-V isn't Windows based and is a purpose built OS from the ground up. It's only required one security patch so far.
    Although it is a bare metal hypervisor - and thus a seperate OS in it's own right - however I was under the impression it was similar to Xen which requires an OS install in Dom-0(?) for some device drivers and system management. Hyper-V requires a Windows host install for the same reason, even if it is just Windows Server Core, I believe thats what the freebie download comes with. This basic Windows host OS install will then require some CPU and memory resources.


    I skimmed through the first article you linked to. Very interesting, it's got me re-thinking my Hyper-V plans. It mentions known compatibility issues with running Hyper-V on a domain controller. Do I keep the hyper-v servers and the NAS/SAN off the domain, or do I make the NAS/SAN box a domain controller for hyper-v to authenticate against? Or do I bite the bullet and run a seperate dedicated DC server?

    Wish I'd found out about ESXi before starting down the Hyper-V route now. The whole reason for wanting to use Hyper-V was purely not being able to afford ESX!

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