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7 Replies Latest reply: Nov 5, 2012 9:32 AM by budachst RSS

OVM Virtual Michine Management Questions. Required to make decision on dep.

972076 Newbie
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Hi Guys,

I'm new to OVM 3.1.1 and have been testing the product for about a week as we are looking at making a decision on whether or not we will be deploying it in production. I have the following question about the latest release (which i'm running) and need to know if the features below are supported as a few of them dont seem to be from the tests I have performed:


All the question are around live Virtual Machine management (i.e the VM is running).

1- Live Virtual Machine disk expansion
2- Virtual Machine Live addition of new hard drives
3- Virtual Machine Live addition of new NIC
4- Virtual Machine live expansion of RAM and CPU.
5- Virtual Machine Snapshots on NFS, Fiber Channel and iSCSI.
6- DRS live migration for load balancing.
7- Virtual Machine live storage migration from one repo to another on NFS, iSCSI and Fiber Channel.
8- Perform a graceful shutdown of the VM through OVM Manager or OEM (i.e through specific tools in the VM, without having to log into the VM).
  • 1. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    user12273962 Pro
    Currently Being Moderated
    1. Never tried but I would say it depends on what guest you are running. Don't expect to actively resize any disk on a windows guest.
    2. Yes. Again. Success would depend on the guest.
    3. Yes.
    4. Yes.
    5. Not necessarily snapshots but you can certainly clone Guests. They must be stopped. You can certainly use you storage products "snaphot" features. You could create a repo "share" for each guest and do individual snapshots. I've thought about it. If you have a lot of guests..... then its a lot of trouble to setup but very little maintenance once you do.
    6. Live migration are supported. I don't know why you are throwing load balancing in the mix.
    7. Not that I'm aware of. Why would you? Can you do this with any product? Underlying storage can certainly support this but I am uncertain this has anything to do with any VM.
    8. Yes. "Shutdown" from the VM Manager does a graceful shutdown. "Kill".... is like removing the power cable.
  • 2. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    budachst Pro
    Currently Being Moderated
    Hi,

    additionally to what has already been said, I'd like to add something to 2,3,4 and 5: as most of them only make sense when running a PVM guest, 4 is even exclusive for PVMs. You won't be able to add more CPUs or RAM to a running HVM, which would include a Windows guest for that matter.

    6 seems to be storage specific and should/must be transparent to OVM, but I guess that's the same with all virtualization platforms. I am running a multipathed iSCSI SR on one of my VM clusters. The questions may be: will you get this with OVM? No, but you can do it yourself.

    7 what do you mean by "Virtual Machine live storage migration"? You can't live migrate a VM (and any of it's components) to another storage repository - you will have to shutdown the guest first.

    cheer,
    budy
  • 3. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    972076 Newbie
    Currently Being Moderated
    Hi user12273962 ... commenting on your reply:

    1. Never tried but I would say it depends on what guest you are running. Don't expect to actively resize any disk on a windows guest.
    Why not? I would expect this from an enterprise level virtualization product as this has been a daily task i;m doing using a different virtualization product.

    6. Live migration are supported. I don't know why you are throwing load balancing in the mix.

    Indeed I will have to bring this into the mix.. I would expect the DRS cluster to load balance the VMs across the OVM servers if the load was too heavy on one node... isn't that called load balancing? and isn't the migration of the VMs to achieve this load balancing called live migration? I read on other blogs that OVM only supports load balancing for the initial placement of the VMs on the power-on of the VMs... I also need live migration while the VM is running to achieve a load balanced DRS cluster..

    7. Not that I'm aware of. Why would you? Can you do this with any product? Underlying storage can certainly support this but I am uncertain this has anything to do with any VM.
    why would I? how about if i needed to migrate the VM files to another SAN that has a repo presented to this server pool to do maintenance on the SAN?


    8. Yes. "Shutdown" from the VM Manager does a graceful shutdown. "Kill".... is like removing the power cable.
    OK, what system process on the VM initializes the shutdown? what "tools" are used?
  • 4. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    972076 Newbie
    Currently Being Moderated
    Hi budachst, Thanks for your answer buddy..

    things are starting to make more sense here...

    so, my understanding to the VM modes in OVM is that there are 3 domain modes:

    HVM, PVM, PVHVM..

    So, Windows VMs will be under the domain type PVHVM.. which is similar to HVM but with additional paravirtualized drivers... so if i install these drivers, will I be able to perform the hot add/expansion of a Windows VM CPU/Memory disk drive or NIC?

    around your comment below:
    "6 seems to be storage specific and should/must be transparent to OVM, but I guess that's the same with all virtualization platforms. I am running a multipathed iSCSI SR on one of my VM clusters. The questions may be: will you get this with OVM? No, but you can do it yourself."

    So the answer to whether or not OVM can load balance the VMs across the server pool's OVM servers is "NO"?

    You asked me what I mean by "Virtual Machine live storage migration"... this is similar to vmware's Storage VMotion... migrating the VM disks to another repo that is presented to the same storage pool while the VM is turned on...
  • 5. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    budachst Pro
    Currently Being Moderated
    The Windows PV driver only cover the networking and disc devices. They speed up both networking and disc access/throughput and bring them mostly ip to speed. However, they don't allow for anything else, like changing the amount of CPUs or RAM at runtime.

    6/7 - Yes, it's "No". ;)

    If you absolutely need those, you'll might have to go with VMWare, then.
  • 6. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    user12273962 Pro
    Currently Being Moderated
    1. First, you must realize that different operating systems react differently to disk resizing. Surely you know this. If you don't.... then you're already behind the "eight ball". This has nothing to do with any virtualization platform. You may be able dynamically expand virtual disk but this doesn't mean the OS will use it. I don't care what you add to a "guest" VM.... you're never going to get past certain OS limitations. Expand the disks all you want.... this doesn't mean that the VM guest OS will actively address the resize space without a "reboot". I've even seen non virtualized linux refuse to see a expanded disk after forcing a bus rescan. Such was/is the need for guest side products like "PowerPath".

    6. Oracle VM will load balance VM guests across CPU cores/RAM of the individual servers. UNLESS... you are using CPU pinning to hard partition your server. Which you must do when running a Oracle Database. You can set minimum/max settings and priorities on each guest. A clustered pool with HAL enabled, will give you fail over live migration of guests but not load balancing across multiple servers.

    Having done a lot of load balancing in my life.... I think you're being a little picky. There are many ways to load balance systems. You should consider max performance when allocating guests to any VM server. You should not over commit VM guests resources greater than MAX capacity of your individual server. If you MUST do this. Then use another product and go ahead and pay TONS more for it. In the end, I'd say you're really ignoring your job and expecting something else to compensate for it. Check out VCE. I'm sure they would love to set you up in a multi million dollar VBlock product.

    7. This is not how any VM product I know of works. You don't move the repositories to accomplish this. In VMware you can do something similar but you have to have the hardware for it. Its not something that is practical with just the "VM product" itself. Again. A Vblock will but expect to pay for it.

    8. You use the VM manager. You can also shutdown your guests from within the guests themselves.
  • 7. Re: OVM Virtual Michine Management Questions. Required to make decision on dep.
    budachst Pro
    Currently Being Moderated
    +1

    …and please let me add, that I am totally into OVM, due to it's simplicity and it's performance - not to mention the costs. It surely is still a bit rough around the edges and there're also some features missing, that others might need, but it's performing exceptionally well and is easy to maintain.

    You get access to almost anything on your VM servers and what can't be done using OVM Manager, can either be done via the OVM cli directly or by using OS scripting - if everything else fails.

    …I have to admit though, that I am a terminal person anyway, so this really is no inconvenience to me. If you browse the forum a bit, you will likely see that most of the questions gather around local hard disk storage and issues with the Java VNC plugin, but there are no real deal-breakers there, afaik.

    Remember, the OVM Servers are Linux boxes, and as much as Oracle would like to treat OVM as an appliance - it yet isn't one and regarding my experience with Oracle products, it won't be anytime soon, which make OVM attractive to me. You're free to do anything to your system, but you need to be sure you understand what you're doing and what it causes to the product - as always.

    This is what I like about OVM ;)

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