£10K

[dhicks]

I will concede that a SAN is not technically required for virtualisation, but it should be considered as a primary component of any size virtualisation project. Not only does this system allow the flexibility to present storage dynamically based on need, but also the combined spindle count, cache and controller configuration in such a system will deliver a higher level of IOPS (which is the holy grail for virtualisation) , when compared to a stand alone systems.

The part that provides the high I/O is the spindle count, cache and RAID controller - for a typical school, a single (large) server will provide more than enough processor power, so there's really no point in putting those disks and RAID controller on the other end of any kind of network connection, just connect them directly via SAS / SATA. There's no point scrimping on the equipment, so buy brand-new multi-processor, dual power supply servers with as much RAM as you can afford (although, in the context of someone having £10,000 to spend now, you could always add more RAM later), but you don't need a SAN. The second server needn't be as well specified, just enough to run the essentials to keep your network running while you get the main server back up if it conks out. Dynamically presented storage (LVM or similar) is typically handled by the virtualisation system itself.

Real-time disk cloning between two physical locations is, of course, ideal, but in my experience most schools can accept maybe half an hour's downtime in the event of a diasaster while you boot up a VM on a second server, trading off that potential downtime against the cost / palavar of implementing real-time disk mirroring.

This is in addition to the obvious benefits of "real" high availability, such as seamless failover in the event of a host failure and not having to rely on copies, most of which will only be in a “crash consistent” state, which does not guarantee a smooth failover.

Being able to take proper backups from snapshots of virtual machines is a feature of the virtualisation system - you need something that supports quiesced snapshots, which the free versions of VMWare and XenServer both seem to do these days.

[glennda]

Being able to take proper backups from snapshots of virtual machines is a feature of the virtualisation system - you need something that supports quiesced snapshots, which the free versions of VMWare and XenServer both seem to do these days.

You can't use veeam on Free ESXI its not supported.

[dhicks]

you don't need a SAN

Sorry, that should probably read more like "the original poster probably doesn't need a SAN for the scale of system he's building for the budget he has". You might well be running a larger system, or one with higher processing needs - once you hit the point where you need more VMs than will realisticly fit on one server then you need shared storage. I assume you're over at Alton Sixth Form College, which I can imagine has pretty large-scale processing requirements.

[dhicks]

You can't use veeam on Free ESXI its not supported.

Thanks, handy to know - I've not used VMWare, I just vaugly assumed it was like XenServer where you can just SSH in and write whatever you want to/from the block devices associated with your VMs.

[synaesthesia]

You can't use veeam on Free ESXI its not supported.

Erm... we have been for yonks... works fine on our 4.1 and 5.whatever hypervisors.

[rich_tech]

At this point in time/line in the sand, I would not say that our processing requirements are massive, as I said earlier, our app usage is pretty low across the board, high end stuff is run by our LEA as I said earlier, stuff with us is spread out over the existing hardware we have quite widely, some are one process a server(not ideal), some are two(not much better imo), but looking forward, our school is expanding slowly and surely and I think that myself and @garethedmondson both want a solid base we can build upon and scale upwards/forwards eventually, I think if we go down the VM route (which I think is best for us, SAN or not, we can move our servers around without much hassle when their virtualised, at least as far as what I envisage)

Its been a case of revisiting our plans and evaluating the road we were going down here, as we head towards the new year, I see the good points and the bad that you have all raised so far, so thanks for the input all so far, much appreciated and a lot to consider still.

[garethedmondson]

At this point in time/line in the sand, I would not say that our processing requirements are massive, as I said earlier, our app usage is pretty low across the board, high end stuff is run by our LEA as I said earlier, stuff with us is spread out over the existing hardware we have quite widely, some are one process a server(not ideal), some are two(not much better imo), but looking forward, our school is expanding slowly and surely and I think that myself and @garethedmondson both want a solid base we can build upon and scale upwards/forwards eventually, I think if we go down the VM route (which I think is best for us, SAN or not, we can move our servers around without much hassle when their virtualised, at least as far as what I envisage)

Its been a case of revisiting our plans and evaluating the road we were going down here, as we head towards the new year, I see the good points and the bad that you have all raised so far, so thanks for the input all so far, much appreciated and a lot to consider still.

Well even with what Richard has said and what has been discussed on here today - I'm none the wiser. As I said - might be easier just to replace boxes. Box for box and so on.

Gareth

[dhicks]

looking forward, our school is expanding slowly and surely and I think that myself and @garethedmondson both want a solid base we can build upon and scale upwards/forwards eventually

You have a point there - if you buy a SAN-based VM hosting system, however much you pay you're accounting for that money over at least 3, 5, or (you'de hope) 7 years. I can't imagine what the average school needs from such capable system quite yet, but on the other hand if schools are all buying well-specified VM hosting machines, maybe we should start thinking up something fun / useful to do with all that spare processing capacity. People keep on going on about "the" cloud, but there's the potential here somewhere for all this spare capacity to be pulled together into some kind of "school cloud" - using the spare capacity of a distributed bunch of machines for interesting stuff.

[glennda]

Thanks, handy to know - I've not used VMWare, I just vaugly assumed it was like XenServer where you can just SSH in and write whatever you want to/from the block devices associated with your VMs.

you can ssh in, veeam works in a variety of ways for accessing the data so it depends on which was it is setup. I believe it works with the free version but VMWare don't want them to do it.

[glennda]

Well even with what Richard has said and what has been discussed on here today - I'm none the wiser. As I said - might be easier just to replace boxes. Box for box and so on.

Gareth

but you would have wasted resources somewhere. Personally I would recommend two (ideally 3) host with shared storag, and cheapest gb to £ storage you will find is custom made and running software for it.

[garethedmondson]

@localzuk - Your PM box is full. Cannot send direct until you empty a bit of it :-)

Gareth

[glennda]

Erm... we have been for yonks... works fine on our 4.1 and 5.whatever hypervisors.

what version of veeam tho? it may work in earlier versions of veeam but its not supported, and in later versions you get an error.

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