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  • gtrider - Tuesday, August 26, 2008 - link

    Virtualization of I/O intensive servers is *still* not a very good idea, but the technology is almost there...
    I say the caveat to that is on toy servers its not a good idea,
    system z is quite virtualized and by nature of the system tend to be io intensive. Its a shame techies overlook it.
  • zdzichu - Monday, August 18, 2008 - link

    Xen, ESX, Hyper-V. Don't forget about native Linux' KVM! With host drivers for virtio from Quamranet it should show it potential. Also available as ready-to-use appliance called oVirt.
  • yuhong - Sunday, August 17, 2008 - link

    The thing about low virtualization performance overhead only possible on the newest hardware can be turned around and be used to help sell them.
  • Darkk - Saturday, August 16, 2008 - link

    I built a couple of linux host based machines running VMWare and been running solid for months. It's cool being able to run the VMWare console in WinXP to manage and build guest OSes. I used to reformat the test PCs all the time and it got old. Now with with Linux VMware servers running I can just create a virtual guest OS and go from there. Pretty slick. My linux boxes are pure text mode, no desktop or gui.

    For testing purposes I got an exchange 2007 server running in VMWare and it's running just fine. Probably due to the fact it's got 8 gigs of ram and currently GSX 1.5 will only let me use almost 4 gigs for each guest OS. The 2.0 beta lets me allocate full 8 gigs for the guest OS but it's a little buggy at the moment. Still promising tho.


  • phinsn98 - Saturday, August 16, 2008 - link

    Phycial vs Virtual performance is a lost argument. When I can run 70 servers SQL, EXC, CTX and 25 VDIs on four hosts with HA and DRS on a single rack with no major failures in three years and no performance issues that the end users can speak of then the physical box performance argument doesn't stand a chance in my opinion.

    I BELEIVE

    I don't argue that a phycial box running a IO intensive app might perform better but at what expense. (server, licensing, power consumption and maintenance) In the Virtual world build the server from template (20 minutes) give it a name and IP and load your app. Have a nice day. No more maintenance, no more power consumption. Have a nice day. Try and run a physical box at 80 to 90% of it's physical resources in one year and watch it fall on it's face. BAD DAY

    I was not the biggest proponant of virtualization but I've seen it and when you work in an environment where all of your servers and VDIs are manageable from one interface and don't fail, it's a beautiful thing.

    If you want to compare something then do a comparison on the competitors of VMWare.

    Windows IT Pro is currently doing a comparison and I have to say they are pretty biased (SAD) they do a good job of overlooking MS shortfalls with their latest Virtual product like how difficult it is to get it up and runnig compared to ESX and no real VMotion capabilty.

    Just my 2 cents

    For what it's worth I've reading this site, promoting this site since it came on board. Thanks for all the hard work and helping me grow and learn.

    DB
  • InternetGeek - Thursday, August 14, 2008 - link

    I'm not an expert in virtualization so it's possible my question is completely off, but Do you guys have time to add Virtual Box to your tests? http://www.virtualbox.org">http://www.virtualbox.org
  • crewslee - Thursday, August 14, 2008 - link

    I have not had much experience with virtual boxes and personally only use it for running ancient applications on top of xp, virtual box is excelent for the casual user.

    Recently an IT server hosting company for one of our slightly more important customers moved all their servers to virtual boxes with no consultation and we have had nothing but problems with with it ever since. The worst issues are severe performance losses with OCR and indexing of docements with Zylab ( www.zylab.com )

    So my question is, what is the easiest way to detect that an OS is rinnung on virtual hardware when you only have access to a remote desktop. At the monent i am looking at the hardware reported and using the lists provided by the VM companies to match them up.... boring :(
  • yyrkoon - Thursday, August 14, 2008 - link

    Heh, sorry had to get that out of my system. Although as far back as I can remember, it has been a dream of mine to be able to run Windows on top of Linux, and still get good gaming performance(assuming it was possible with current titles because of how video hardware is/is not accessed).

    I have a friend who used to use a custom Xen kernel with Dell hardware for large deployments of Windows(think thousands of systems). I remember him telling me: "there is nothing cooler than watching 2+ VMs working harder(as in getting things done faster), than just using the bare hardware with a single OS." From what he told me his team modified the kernel for their specific needs, and used GbE equipment for deployment of netinstalls. Performance for them was greater or as good as bare metal in most cases.

    Another person I talk to on IRC once in a while has mentioned that he maintains MANY machines(as in a farm), that all use Xen + Linux software RAID 10 for mission critical data, and that the performance is very good.

    My experiences with many para virtual implementations has not been as good however. Then again I do not have a team to customize a Xen kernel for me, or have countless hours of experience/knowledge of how the Xen kernel works. I also have not had the hardware to use, or the need to really use virtualization for other than my above mentioned pipe dream(first paragraph). Although lately, for me I think I would have to say that parallels at least on a Windows host would have to be one of the best performers. VMware is nice, but in the last couple of years seems to be getting bloated and slow. I do not have any hands on with ESX however, and what I speak of is their server/ Workstation variations.

    With all the 'Virtual hosts' popping up over the course of the last several months though, *something* has to be working for *someone* . . .

  • vvelichkov - Thursday, August 14, 2008 - link

    Virtualization of I/O intesive servers is *still* not a very good idea, but the technology is almost there. It is not the ESX 3.5 that is not ready, but the hardware is still not quite available.

    Currently there is only one hardware combination:
    ESX 3.5 Update 2 + Intel 5400 Chipset + Latest Intel PCIe 2.0 10G LAN Adapters + Latest QLogic PCIe 2.0 8Gbps FC HBAs is a good candidate for ESX host supporting I/O intesive servers.

    What is missing:
    1. Intel 5400 Chipset is Server/Workstation mid-range chipset not available in any serious server platforms from HP / IBM / Dell. Supermicro has good mobos with this chipset, also HP has some low-end models. Waiting for Nehalem based Xeons and proper mid-range/high-end server chipset supporting the latest generation Intel VM related features (VMDq2 / VT-x2 / VT-d2)
    2. Intel does not offer any 1000Base-T NICs supporting PCIe 2.0. There is only one integrated Ethernet controller used on some mobos for on-board Ethernet. Using 10G PCIe NICs is quite expensive (still)
    3. ESX 3.5 Update 2 has support for all the above mentioned second generation VM related features, but still in "experimental" mode.

    Let's see...
  • mlambert - Thursday, August 14, 2008 - link

    If you guys are interested in some performance stats (NFS, FC, iSCSI) for ESX datastores & host utilization, NetApp did a really good white paper in July:

    http://media.netapp.com/documents/tr-3428.pdf">http://media.netapp.com/documents/tr-3428.pdf



  • Jeff7181 - Thursday, August 14, 2008 - link

    Seriously... do any vendors claim you should virtualize an I/O intensive database?

    Some things just should not be virtualized yet. A database server is one of them.
  • JohanAnandtech - Thursday, August 14, 2008 - link

    And now you are part of the folklore too. :-)

    Seriously, just google for "near native performance" and you'll find that Microsoft and Xen are making this claim often.

    VMWare latest ESX 3.5 can virtualize I/O intensive databases in the right circumstances with a relatively low performance impact, but markets it as if every database application is now easy to virtualize. Just click on the links I put in the blogpost above, and you'll see that indeed the vendors are claiming this.
  • abraxas1 - Thursday, August 14, 2008 - link

    I've been working in large VMware environments since the days of 1.5. There is a performance gap but it has been steadily shrinking with each release of ESX. One important thing that I've learned though is that the gap is very dependant on the knowledge and experience of the people deploying your ESX based infrastructure. The less experience your people have, the larger the gap will be. Most of my clients hire me to evaluate their existing infrastructure and advise them on the mistakes they made.

    I also have a rule of thumb to avoid I/O intensive apps when virtualizing an infrastructure. ESX shines when you get MANY servers on one piece of hardware. If you create a VM that requires max memory and cpu, then your density is going to drop significantly. With the latest bulid of ESX (3.5) my estimate for clients is 90% virtualization. That 10% that can't be virtualized are servers with funky hardware, unsupported OS, or massive I/O.
  • JohanAnandtech - Thursday, August 14, 2008 - link

    Good Feedback, clearly based on realworld experience. That is indeed the message that we should sent to those evaluating Virtualization.

    ESX 3.5 brought "near native performance for all workloads" a little closer, but we are still not there. I have seen companies move their SQL servers back to native as virtualization created too much overhead. I fully agree however that 90% of the workloads do well on ESX 3.5. I still have to investigate fileservers. Although they are low CPU usage, the intensive use of the filesystem could wreak havoc on a hypervisor. It does so on Xen and other opensource hypervisors, I yet have to try ESX.
  • SammyJr - Thursday, August 14, 2008 - link

    We have two file server VMs that are replicating with DFS Replication. Performance is great, serving about 800 users. We've have no complaints about speed and files open quickly.
    Many of our users work with large image files.

    We're on a tight budget so our VMWare storage is direct attached using Adaptec SAS cards and SATA drives. Our servers are white box dual Clovertown and dual Harpertowns.

    We've found that ESX is quite good at scheduling I/O.
  • ChrisG - Thursday, August 14, 2008 - link

    Thank you.

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