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On 02/06/10 21:34, Gordon Henderson wrote:
On Wed, 2 Jun 2010, Rob Beard wrote:Hi folks, I was wondering if anyone has had a look at Proxmox VE at all? Basically I've been given the task to look at implementing a mirrored server (that is, two servers which are identical and if one fails, the other takes over). I gather the term these days is failover. Now the last time I looked at anything like this was when I was given a demonstration of such a thing on Novell Netware 4 (so you can guess how long ago that was). One of the issues is that the servers are going to be running a flavour of Windows Server (probably 2003), at least for some stuff.Linux-HA is well established... Running a Win server inside a Linux with (e.g.) KVM, then having another, then failling over one to the other ... Hmmm.. DRDB http://www.drbd.org/ will replicate disks over a LAN, so I guess that in-theory, it might work... It depends on how the Windows VM is going to react - my guess is that you'd have to keep it shutdown on the spare, then boot it when the main one fails - when it'll probably have to do it's equivalenr of an fsck before launching applications. (That's typically how you might keep a Linux-HA host going - just have the kernel running then when the master has died start the applications on the secondary, but assume the same IP addresses - it's not instant, but I can 'boot' one of my VoIP servers in under 5 seconds which is good enough.
Hmm, I'll have a look. The Windows servers take a couple of minutes to boot, just long enough to wander down to the coffee machine and back.
On the commercial side of things the only solutions I have found are Double Take (it basically runs on a Windows Server and any changes to one server get applied to the other), VMWare ESX with VMotion and some VMWare console package (VMotion and the console package cost money) or Windows Server 2008 with Hyper-V.If you're using Windows, maybe it's better off with a native Windows solution..
That's what I was thinking. I like the idea of Double Take but it's expensive. Personally I think I'd be happy just keeping it as it is but one of the powers that be likes this mirrored idea so I figured I'd at least have a look into it. Maybe in the long run the company could possibly move over to more Linux based stuff (especially considering how Windows Server 2003 isn't available anymore, and it's all Windows Server 2008 R2 and Exchange 2007).
Doing a bit more searching though came up woth Proxmox VE which I gather is available as a distro which is based on Debian Lenny, or can be added to an existing Lenny install.Does it really have to be windows? Is there nothing native in the Windows world? I wonder if adding Linux into the equation might just make it harder in the long-run... Having built and run HA platforms, it can be a bit of a faff - sometimes I just wonder about various plan B's... think about what it is that you're protecting against and how long a down-time can you withstand? Redundant PSUs... RAID or external SAN systems Even servers with hot-swappable CPUs... The biggest problem-thing I've found in a single system server is motherboard (or some vital component that can't be replicated) going phut. Or a software fault - when do you reboot the server or have the hot-spare take over? Too many questions.. and I bet there's a financial constraint at stake too... Still - a quick look at Proxmox VE suggests it's got everything rolled into one bundle - kernel, distro, drdb, clustering, etc. so you never know...
I see your point, I figured if I can get some hardware together I might have a play but having lots to do as it is I'm thinking at least in the sort term it might be easier to keep it more simple and have an e-mail server, a file server and then the *shudder* Sage servers separate.
All I originally wanted was to get another server for the poor CAD & Marketing folks who have been given a small amount of space on one of the finance servers (even a NAS with RAID would have done the job, one such beastie I've seen is about £150, and has RAID and Gigabit Ethernet in it).
Rob -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html