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Xen, KVM or OpenVZ for private server?
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Xen, KVM or OpenVZ for private server?

pylodepylode Member
edited October 2012 in General


I've purchased a dedicated server with 8GB RAM, Intel Celeron G530 CPU and will be using virtualization/container technologies on it.

I've had experience with OpenVZ and management via vzctl and am quite happy with it. However since i will be running some java programs (minecraft server, cloudfoundry) etc OpenVZ has, in the past been quite annoying with its java memory usage.

What would you suggest i use for Virtualization? I personally would prefer Xen PV or KVM, but OpenVZ might be fine (and faster) for this.

Please note i can't afford to purchase any commercial VZ,Xen or KVM panel (SolusVM, VePortal). I've looked at HyperVM but it doesn't say it supports CentOS 6.

My question is, if you were in my situation. Would you use: Xen, KVM? or container based OpenVZ?

Also, if anyone can suggest a way of managing Xen or KVM servers (preferably a web interface? that is also free) please do so.



  • Openvz with vzwap would be alright.

    but your best be is xen.

  • pylodepylode Member
    edited October 2012

    I personally do want to use Xen PV (Not HVM, so probably not KVM) but i've been trying to get this working on a local vmware vm (with VT-X enabled) on CentOS 6.3 x86_64 but i've been getting libvirt compilation errors (followed guide: (rpmbuild -bb libvirt.spec).

    OpenVZ with VSwap looks great, but i'm still not sure if this'll work out, (one vps will need to run CloudFoundry)?

  • The openvz with vswap should work just find for java. I have see multiple people run it now.

  • Thanks @24khost, would like to hear other peoples opinions, suggestions too though.

  • jhjh Member

    Sounds like OpenVZ will be easiest for you as you're not using a panel and you know how it works already.

  • OpenVZ works fine for java. Just give the container lots of privvmpages. - The oldest post to host VPS provider
    Thanked by 1klikli
  • I think Xen would be your best choice.

  • wdqwdq Member

    I run Citrix XenServer on all of my dedicated servers. It might not be the best option if you're planning to sell VPS's off of the server (since you can't oversell RAM/storage with XenServer), but otherwise XenServer is great.

  • Proxmox is the (open source) way to go, has KVM and OpenVZ in a single kernel. Need something easy to manage but still quite professional or just want Xen? Go with XenCenter Is it non-commercial and can you be bothered? Go with VMware ESXi

  • MaouniqueMaounique Member
    edited October 2012

    I also say proxmox is good, for Xen use XCP (both PV and HVM).



  • Are Celerons VT enabled? I thought it was only I series and Xeons are.

  • MaouniqueMaounique Member
    edited October 2012

    Yeah, I checked and that one is. Celerons today are not what they used to be. It always reminded me of M


    Thanked by 1rchurch
  • jarlandjarland Administrator

    Although it's pretty much been said, I'll weigh in as I have a dedicated that I run proxmox on for my own usage.

    OpenVZ is going to get the most out of your hardware. It performs great, and you can stretch more out of the system. It's not going to be a huge difference to where you're going to see a true virtualization perform significantly better or worse. It's just a little bit more efficient in my experience.

    I'm using A2Hosting right now for shared, love it. Referral link.

  • MaouniqueMaounique Member
    edited October 2012

    Proxmox offers ease of use and larger choice while pure OVZ offers speed. I have a proxmox colo too for my own usage, I would say it is taxing the old dual xeons at about 10% at least. Also, for a secret project, I am working with one on the Prometeus Atoms, it does work, I would say better than expected, but, of course, only for OVZ. However, OVZ under Proxmox is still very snappy. M


  • I have just checked and it seems that VT-x is standard on all of Intel's latest offerings, except perhaps Atoms. I was looking towards AMDs as it is standard across the line. I will consider a cheap Celeron or Pentium for my next PC. I hope the boards are too.

    PS. How does VT-d help? It appears to be available on only i5s and above

  • @rchurch vt-d means a VM can be assigned real devices thus improving performance (no emulation needed). This also improves security - security weaknesses exploited in (for example) network cards only impact the VM they are attached to (without vt-d, the underlying host and thus all VMs are pwned)? More from Intel here:

    "Go cheap on rarely used things"

    Thanked by 1rchurch
  • KuJoeKuJoe Member, Provider

    For our internal servers we switched from Xen to KVM then finally to OpenVZ. OpenVZ just performs better and is easier to manage in our experience.

    -Joe @ SecureDragon - LEB's Powered by Wyvern in FL, CO, CA, IL, NJ, GA, OR, TX, and AZ
    Need free hosting? Get AFreeCloud
  • I'm not too knowledgeable in virtualization, but from what I hear from a lot of people OpenVZ has greater performance over other choices. I use it myself most of the time and I don't really have any issues with it apart from the lack of ability to modify the kernel.

  • tinyraytinyray Member
    edited October 2012

    for those interested,

    "A Synthetical Performance Evaluation of OpenVZ, Xen and KVM," IEEE Int'l computing conference, 2010...,

    Through measuring and analyzing OpenVZ, Xen and KVM with SPEC CPU2006, LINPACK, Kernel compiling, RAMSPEED, LMbench, IOzone, Bonnie++, NetIO, WebBench, SysBench and SPEC JBB2005, we found that OpenVZ has the best performance and Xen follows OpenVZ with a slight degradation in most experiments, while KVM has apparently lower performance than OpenVZ and Xen. Furthermore, this indicates that operating system-level virtualization and para-virtualization have some apparent advantage on data-intensive applications such as disk I/O, net I/O, web server, database server and Java server. However,....

  • Well, OVZ is not really virtualization, just a slicing of a bigger machine with some kernel modules to mimic some aspects of a real virtual machine, so, not a surprise there. However, .32 kernels cannot take so much beating like the .18 ones and are crashing much more frequently under load, especially if there are many containers on the node. No wonder some providers still stick to .18 kernels even tho the .32 rewrite is offering more options and mimics a VM better in many aspects. Regarding Xen and KVM, if we talk about Xen-PV, yeah, that is consistent with the theory, however, Xen-HVM does not perform better compared with KVM on VirtIO drivers in my view, they are about the same. M


  • KuJoeKuJoe Member, Provider

    @Maounique said: Xen-HVM does not perform better compared with KVM on VirtIO drivers in my view, they are about the same.

    Xen HVM and KVM are pretty much identical in performance. Xen HVM will outperform KVM by a slight different in some tests while KVM will outperform KVM by a slight different in other tests but in all performance benchmarks performed you'll see they are , for all intents and purposes, equal.

    -Joe @ SecureDragon - LEB's Powered by Wyvern in FL, CO, CA, IL, NJ, GA, OR, TX, and AZ
    Need free hosting? Get AFreeCloud
  • marcmmarcm Member
    edited October 2012

    @KuJoe How does KVM, when running virtio on the guest and deadline scheduler on the host compare to XenPV in your opinion/experience?

  • So at first i tried OpenVZ, but java didn't run well (even with vswap). Xen isn't really supported on RHEL/CentOS 6 anymore (officially anyway), so i decided to reformat and go with KVM + LVM partitioning.

    Besides a small performance hit, i'm glad i chose KVM (HVM).

  • @smooch1502 How is the I/O speed and responsiveness with KVM?

  • What about Cloudmin GPL for KVM ?

    New VPS Offers | KVM | Germany | 70GB HD | 768MB RAM | Unmetered BW

  • pylodepylode Member
    edited October 2012


    Not that good really: [[email protected] ~]# dd bs=1M count=128 if=/dev/zero of=test conv=fdatasync 128+0 records in 128+0 records out 134217728 bytes (134 MB) copied, 1.78848 s, 75.0 MB/s

    Mind you, i don't run much.. so its fine for me

    PS: I am running a minecraft server on the same VM as i did this test

  • @smooch1502 That's perfectly fine. If I may give you some advice from my own experience: set elevator=deadline in your bootloader (kernel line) and the guests to elevator=noop and don't use caching on the guests. I/O should be very consistent with these settings :)

  • @marcm Too bad the CPU aint that great, with the RAM + HDD here, could've sold some LEBs

  • @smooch1502 you still can, but I wouldn't have on my personal server anyone who I don't know - so I guess it would be OK for friends, family, etc. - just my opinion :)

    The settings that I've show you are well tested and work great for me on all of our nodes.

  • @marcm So you think the CPU is fairly good for LEBs?

  • @smooch1502 KVM + a dual core CPU, it's hard to say. It's up to you, but I wouldn't offer it as a commercial product. For my needs for example a dedicated server like yours would be more than enough, but I wouldn't like to share it with others (like I said, only friends, people who you know, and family).

  • KuJoeKuJoe Member, Provider
    edited October 2012

    One of our internal OpenVZ nodes is running an Intel Atom 230 with 2GB of RAM with a 5400RPM laptop hard drive. Not the best performance but it's not used for public facing stuff and the most demanded process running on it is java (CrashPlan).

    -Joe @ SecureDragon - LEB's Powered by Wyvern in FL, CO, CA, IL, NJ, GA, OR, TX, and AZ
    Need free hosting? Get AFreeCloud
  • @marcm Don't think i'm going to bother selling any then. As you said, it's probably best to just keep this for personal use.

  • Just FYI, OpenVZ (Even with VSwap) + Java just don't mix, can only use about half of the allocated RAM. ^^ Not overselling

  • @smooch1502 said: Just FYI, OpenVZ (Even with VSwap) + Java just don't mix, can only use about half of the allocated RAM. ^^ Not overselling


    [[email protected] ~]# free -m
                 total       used       free     shared    buffers     cached
    Mem:          1024       1023          0          0          0         29
    -/+ buffers/cache:        993         30
    Swap:         1024        374        649
    [[email protected] ~]# uname -a
    Linux 2.6.32-042stab061.2 #1 SMP Fri Aug 24 09:07:21 MSK 2012 i686 i686 i386 GNU/Linux
    20:11:54 [INFO] Maximum memory: 1,024 MB
    20:11:54 [INFO] Allocated memory: 1,023 MB
    20:11:54 [INFO] Free memory: 189 MB - The oldest post to host VPS provider
  • @smooch1502 said: can only use about half of the allocated RAM.

    Why? You may want to contact your provider about having their VPSes setup incorrectly somehow, if you're experiencing this.

  • I am the provider, haha.. I've looked at just about every setting i can, i can only run about one java instance in the VM unless i assign each very low memory -Xmx, -Xms

  • @smooch1502 Please show us your /proc/user_beancounters from inside the VM - The oldest post to host VPS provider
  • OpenVZ with vswap has been working great with Java. There's not only min/max memory settings, but garbage collector, permgen amount, codecache amount, native heap amount, threads and thread stack size, etc.

    Lots of settings. It depends on your app/code.

    Serving you the best VPS, Web hosting, dedicated servers and more - Cloud Shards | Query Foundry
    We operate the network AS62638 | Available in Syd AU and Dallas, Los Angeles and NYC USA
  • @smooch1502 said: Just FYI, OpenVZ (Even with VSwap) + Java just don't mix, can only use about half of the allocated RAM.

    Bullshit. You/your provider must be doing something wrong.

    ~ Jimmy VortexUnit. Who likes poptart.cats?
  • @lele0108 using the vzctl tool, how would i tune the container to work better with java? vmguarpages, vmprivpages all set like

    except i also set vswap to about 512 MB RAM and no burst, eg : vzctl set ${cid} --privvmpages 256M --save

  • First make sure you have at least 2 vCPU. You do need a bit of vswap, indeed, that is good for linux to have a swap. Java will always have an issue with OVZ, but other than networking which cant usually be fixed due to the way venet works, throwing more pages at it will help as well as giving 2 vCPUs.


  • It's kinda obvious that @smooch1502 has 512MB or 256MB assigned to his container, so he can't use all the RAM or Java will cry about lack of RAM. Burst and vSwap will help you bypass that though.

  • Alright, i might go the Xen PV route, no issues with java from what i know. KVM HVM is overkill for me right now

  • MaouniqueMaounique Member
    edited December 2012

    An excellent choice, if you wish to automate it for free, look at cloudmin GPL, just dont install it on debian, there are issues as it will always try to HVM it instead of PV. XCP works too and offers more control but needs extra tools to install on an windows pc for best experience and it is not really compatible with Xen formats.


  • Which OS is preferred for cloudmin gpl xen pv lvm?

  • MaouniqueMaounique Member
    edited December 2012

    centos 5. it works on ubuntu 10.04 too, with one minor problem, cpu weighting for guests, but needs some adjustments, for best oob experience, centos 5 as host, At partitioning make sure you create the vg but leave the space unpartitioned.


  • I love KVM personally..over XEN. My experiences with XEN end user exp haven't been all that good.

  • @smooch1502 said: except i also set vswap to about 512 MB RAM and no burst, eg : vzctl set ${cid} --privvmpages 256M --save

    Then you limited the container to allocating 256mb. - The oldest post to host VPS provider
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