We are planning a slow migration from VMware (and third party apps) to open source alternatives (free would be great).

Basically, we want to start with some little cluster lab, then migrate the production environment (35+ ESX, 1500 VMs) in the future (X years, there is no hurry... yet)

Our bet is CentOS/Scientific Linux as the operating system of choice and KVM as the hypervisor.

The vCenter alternative we are thinking about, is Convirt, but we don't know if all the features we use in VMware will be supplied by Convirt (HA, DRS, clustering,...), or we should try some other alternatives (any ideas?)

The monitoring is being replaced by Nagios and the backup/replication will be replaced by some scripting magic.

So, is there anyone who can give us some advices, or in a similar situation?

PS.- This is my first question in serverfault, and my english level is not so good, but I hope the question is understandable.

PS2.- I forgot to mention that we provide also VDIs. And the alternative we've been thinking is Spice.

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    For the record, as far as first questions go, especially for a non-english native speaker, this is very good :) – Mark Henderson Oct 14 '11 at 7:47
  • As for the question, what are your guest operating systems? Are they all Linux/Unix or is there some Windows/other in the mix? – Mark Henderson Oct 14 '11 at 7:48
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    I guess the next question is why - what are you looking to achieve? I have not yet seen a virtualisation solution that is anywhere near as all-compassing as a properly licensed vcenter installation. Hyper-V hates Unix, Xen and Windows have a love-hate relationship, KVM I don't really know about, but I have never, ever seen an interface as easy to use as vSphere's (from both scripting and gui). So we would also need to know what you're willing to sacrifice. – Mark Henderson Oct 14 '11 at 7:53
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    It's not a phylosophical (neither a money cost) question, it's about replace some virtual infraestructure with a cheaper alternative, mantaining (in the possible ways) the quality. If there are open source, not necessary free (money talking) options, we (well, not me, my bosses, I'm just one sysadmin) evaluate that and pay for it. The question about the money cost is because (as I said before) sometimes in the future the decision could be licenses or staff. And speaking about Microsoft, the licenses are not cheap (I really don't know, I'm just a sysadmin, that's what I've been told). – minWi Oct 14 '11 at 17:00
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    Your English is far better than we often see from people who speak English natively. – John Gardeniers Oct 14 '11 at 19:30

Having recently gone through the same song and dance with my own management ("VMWare is really expensive! Check out what OSS options there are out there.") I have some observations to share.

  • I/O performance does vary by hypervisor, though CPU performance is much less variant.
    • In general, 'thin' provisioning is a great way to dock I/O performance. Some (KVM until very recently) are pretty bad about this.
  • The big three non-VMware alternatives (Xen, KVM, Hyper-V) all have some kind of vMotion-like technology, though there are limits.
  • Some are very sensitive to CPU architectures, and don't allow live-migrations to systems that aren't identical. VSphere gets around this with their "Enhanced vMotion Compatibility" technology that dumbs a cluster down to the lowest CPU architecture in the cluster. Not everything else has something like that. This can be a big barrier to expanding your VM plant.
  • A Hypervisor is only as good as its management console.

That last point is the big one. It's all well and good to have 150 KVM instances, but without some kind of automation to move machines around it doesn't do you much good. There are many, many OSS and non-OSS orchestration frameworks out there, a lot of them built on Libvirt. Once you've found a hypervisor that works the way you'd like it to, you'll probably spent just as much time if not longer evaluating management frameworks for something that works the way you need it to.

I've been impressed with CloudStack. It was recently purchased by Citrix, but it's an OSS management framework that (as of a couple months ago at least) has a few features only found in paid frameworks. That said, you do tend to get a much more polished framework when you pay for it; CloudStack is under active development so is rapidly changing.

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  • Thanks! That's the kind of stuff I want when I've asked for that :) I really appreciate your answer! – minWi Oct 14 '11 at 16:52
  • cloudstack currently supports KVM and Xen. Does it also offer tools for live migration, conversion between formats? – John-ZFS May 8 '12 at 15:12
  • @John-ZFS No idea. They've done a lot of work in the 9 months since I looked at them, so you'd have to ask them. – sysadmin1138 May 8 '12 at 16:54

I haven't used it myself but there is Proxmox-VE. According to Hak5, it supports a variety of OS's including Windows. It also supports clustering

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  • I've used it. Wonderful system, but I don't know it compares in detailed feature for feature, with VSphere. It's really growing too. – alphadogg Oct 14 '11 at 14:10
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    Proxmox-VE is a nice interface to KVM and OpenVZ. So in order to use PVE, you would need to check if KVM and OpenVZ would cover your needs. – the-wabbit Oct 14 '11 at 15:04
  • Proxmox VE is one of the alternatives we will try, specially 2.0 version, that promises clustering and some other improvements about earlier versions. – minWi Oct 14 '11 at 16:53

Citrix XenServer is an open source hypervisor and might be a good candidate for you.

There are quite a lot of tools available to manage it, but you may find gaps where you have to spend money where the free/open source tools fall short. However, in comparison to what you get with VMware ESXi, the Free Edition provides quite a bit (Live Migration, for example, comes with the free version of XenServer).

VDI is free for up to 10 desktops with XenDesktop 5.5 Express Edition (trial, then after 30 days, you need to register to obtain a perpetual free license).

However, I think at some point, you will need to spend money, especially with a large implementation such as yours. It's one thing to have a host or two and figure, "well I can get away with a handful of scripts or just do this and that by hand" but with 35+ hypervisors, clustering, failover/recovery, provisioning, etc. all (likely) distributed across several teams (and departments, perhaps?), you have some heavy-lifting to do (as you're probably well aware).

I would also leverage the size of your implementation by engaging with the PR/marketing/communications people wherever you're thinking of going; I can see a juicy case study unfolding here for whatever vendor/organization you decide to go with and they'll likely throw at you all sorts of freebies in service, software, and support to pull this off successfully.

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    Citrix XenServer is economical and stable compared to Vspehre 5.0 – John-ZFS May 8 '12 at 15:14
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    are you saying that vSphere 5.0 is not stable and/or economical? – gravyface May 8 '12 at 17:00

For small clusters (i.e. < 10 hosts): Proxmox: support KVM and OpenVZ, nice web interface. http://pve.proxmox.com/

For large clusters: OpenNebula: support KVM, Xen, vmware hypervisors and use standard API (EC2, OCCI). http://opennebula.org/

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Take a look at Hyper-V. Its not open source but it is free and it will get you most of the things you're looking for. I'm currently running a cluster of 3 servers and several dozen CentOS VMs and I'm loving it.

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I am in the middle of testing RHEV 3.0 (Red Hat's virtualization management offering). Not bad so far.

At the moment it's not Open Source but that is on the roadmap - Red Hat plans to open source the entire management stack in the next year or two.

It is targeted at both server virt and VDI so would be suitable for your deployment.

It is not as advanced as vSphere (as RH admits) but the functionality is pretty good.

Another big advantage for RHEV is it's using KVM and ovirt - no lockin!

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  • RHEV is not using oVirt, oVirt is the upstream, completely open-source version. Similar relationship as with RHEL and Fedora. – M.K. May 15 '12 at 12:58
  • OK, RHEV is built on oVirt, if you want to argue semantics. – MikeyB May 15 '12 at 15:56

What you describe is a pretty large setup, and the fact that you're also providing VDI, makes RHEV the perfect answer to the question.

I am of course biased, so don't take my word for it, get in touch with Red Hat.

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  • We've test RHEV (a RedHat engineer provided us a little lab in our datacenter), but in our humble opinion the money saving comparing with the VMware features (plus the migration) is not enough. To us, it's not an alternative yet (please forgive me, I'm sort of Red Hat fan) – minWi Oct 14 '11 at 9:04
  • well, it's up to you of course, you know best how to count your budget. I do however hear the opposite from many different people who switched to RHEV. Basically, you're after a free solution, that is good enough for an enterprise-class setup. I doubt you'll find anything closer that RHEV for that purpose, unless you're willing to wait for the oVirt project to start and become production-ready – dyasny Oct 14 '11 at 9:30
  • We know for sure that all the features included in enterprise focused products will not be available in open source alternatives (and much less in free apps), that's why I need some advices in what alternatives are featured close to our actual environemnt. We'll take a look to oVirt. Thanks! – minWi Oct 14 '11 at 9:38

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