Thin Client and Virtual Machines Thread, £10K in Technical; Originally Posted by garethedmondson
How about this kit:
2U Supermicro 12 Hotswap Bays, Redundant 1200W Power supplies, Dual
30th November 2012, 01:58 PM #16
And how're you gonna link them together?
Originally Posted by garethedmondson
30th November 2012, 02:00 PM #17
We've been told that for now and until we can afford it that cat6 would be okay. If that's wrong then we cannot afford fibre channels at the moment.
Maybe it would be better if we ditch the virtualisation option and just buy 10 cheap servers :-) Bugger the Eco/green credentials.
How should we be linking them together?
30th November 2012, 02:05 PM #18
I'd say fibre would probably be best for this - no need for a fibre switch if the SAN has enough ports.
However if you're thinking iSCSI you'll definitely need more ports. 4GB to split between storage, networking and machine failover is not gonna be great. at all.
30th November 2012, 02:06 PM #19
I sympathise with zag but it does depend what you call a "SAN". It seems sensible to me to provision lumps of storage via iSCSI on a separate network from user/service traffic. So that could be a small managed switch and a cheapish box running FreeNAS or a basic NAS appliance. I think that would qualify as a "SAN" (storage area network). With Hypervisors in the mix, running guest servers in clusters I want the advantage of vmotion and high availability (or simmilar) , so I need something that will service the IOPS (even relatively inexpensive devices will service the throughput). That tends to mean chucking lots of spindles in a box.
30th November 2012, 02:07 PM #20
Does the SAN have a dual controller? Can be a pain if the controller link fails otherwise.
30th November 2012, 02:10 PM #21
As I said in my PM, we are using Windows 2012 on our storage server and 2 hosts, with SMB3 instead of ISCSI. We have 10GbE for our interconnects. Its expensive unless you have a modular switch to work with I'd say.
FC can be done pretty cheap, but its only any use if you have software on the storage device that supports it properly.
30th November 2012, 02:11 PM #22
most of the systems we are thinking of virtualising are not heavy duty as far as I would categorise them, as our LEA manage the major things at this time (AD/Exchange/anti-virus protection/SIMS) (also view to moving some stuff to cloud based services in the future possibly) though we are looking to replace 9 year old RM hardware in some of the cases, as its on its last legs, 3 most major things at the moment we run are our impero server, printer server (pcounter) and our rebuilding machine - WDS/MDT box lot of the other stuff we run at the moment are fairly small applications mostly on 1/2 per box maximum (obviously on the old RM kit the hard disks are fairly small as well)
30th November 2012, 02:12 PM #23
Thanks for chipping in.
30th November 2012, 02:13 PM #24
So maybe I am just better getting 5 powerful box servers and not virtualising anything. Could be cheaper. I'm sure there are some nice Dell racks out there or some refurbs from ICT-Direct - could save me a packet. The big question is - do I need to virtualise?
30th November 2012, 02:22 PM #25
Just get the 2 servers and skip the SAN, you don't need it. £5,000 should get you a very nice server - multi-processor, multi-core, at least 32GB of RAM, with some high-I/O speed harddrives (15,000RPM SAS drives, if you like). Get two of those and have each one mirror the other's storage, so if one goes down you can simply switch to running the virtul machine images on the other machine. Ideally, of course, your servers would be in two separate physical locations to guard against diasaster. You can mirror storage in real-time, I've used DRBD for that in the past, but it can be a bit fiddly to set up and use in practice, so I'm guessing periodic snapshots transferred between machine might be more appropriate for a school environment.
Originally Posted by garethedmondson
30th November 2012, 02:25 PM #26
Yes you should virtualize, but that doesn't mean you need SANS or separate storage.
Buying 1 extra machine for backups or clones is enough for high availibility.
here's a pic of our setup. Pretty simple really. The 6th server is in a seperate location to prevent a "the server room burnt down scenario".
30th November 2012, 02:45 PM #27
*Cough|* Ebay *cough* 16 x HP ProLiant BL460c w/ 2x Quad-Core Xeon L5420 2.5Ghz BL c7000 Blade Server | eBay
Leaves you with £5k for switches, storage and a lot of power connections.
30th November 2012, 02:46 PM #28
There was a thread on here a while back which suggested we can make life very complicated for ourselves with technology
We used to run our school on 7 seperate physical servers until BSF came along. Now we have a SAN and a dual VMWare cluster configured for high availability, with dedicated iSCSI switches & redundancy all over the place. It was not cheap... the irony is that we are delivering no more useful services or functionality to our end users than we were before BSF; true, we can cope with failure with less down time (in theory) but in the 7 years I ran our old low budget network we had two server failures of around 1/2 day which took out part of our operation. One of these was due to a serverboard dying (requiring cannibalisation of another server), the other a disk failure in a RAID array that took forever to rebuild.
Virtualisation is a techies dream (& nightmare)..... where I work we are pulling out of our managed service , to do this I have to migrate from VMWare to Hyper-V, add another server to the cluster, add extra disks to the SAN, & we need to sort out local & offsite backups. It is going to cost ££££££.... & we still won't be delivering any more services to our end users.
Don't let technology blind you ...... I would happily go back to a simpler environment
Last edited by broc; 30th November 2012 at 02:47 PM.
30th November 2012, 02:58 PM #29
I do not as a rule comment on this board, but in the face of such ridiculous and ill-informed comments that I have witnessed today, I cannot help but bring my many years of virtualisation knowledge in both education and corporate world to bear.
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.
Almost all SANs can also host file data directly using CIFS (SMB) while at the same time using iSCSI for VM disk presentation, which will be more efficient than creating file servers in the virtual world and then saving all the file data to disks within that environment.
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.
In regards server specifications, having a large number of servers with a small amount of RAM such as 32GB is an inefficient waste of hardware has the rest of the system will never be stretched before you run out of RAM.
The whole ethos of virtualisation is to “sweat” the hardware to ensure the most cost efficient use of the investment, and buying servers like that will not accomplish this. It is best to buy say two (or three) servers with a large number of NICS to ensure sufficient bandwidth for both server and storage communication and with say 72GB RAM as a Minimum (96GB+ would be better).
This type of investment is not one you make every day, and your decisions will have to stand the scrutiny of time, so make sure you have all the information at hand before making this leap, and do not fall into the all too common trap of seeing how many servers you can get for the money.
Virtualisation is 90% thinking and 10% deploying, always remember to think quality before quantity and I am sure you will get the results you want.
3 Thanks to Punkfish:
garethedmondson (13th February 2013), meastaugh1 (3rd December 2012), zag (30th November 2012)
30th November 2012, 03:05 PM #30
Good post and I'd agree with most of what you say. However, if you are budget limited (common in schools) then you will have to compromise.
Originally Posted by Punkfish
@garethedmondson - don't forget to factor in appropriate UPS.
Thanks to pcstru from:
sluggster66 (22nd September 2013)
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