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Thin Client and Virtual Machines Thread, Whether to virtualise our main servers in Technical; Originally Posted by seawolf I strongly disagree. I think you would be better served by 3-4 less expensive physical servers ...
  1. #46

    sparkeh's Avatar
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    Quote Originally Posted by seawolf View Post
    I strongly disagree. I think you would be better served by 3-4 less expensive physical servers with good warranties and vendor support and a good backup solution.

    If you're SOLE server ever goes down (highly likely at some point), how long will your ENTIRE environment be down while you obtain a replacement server? Whereas, the likelihood of having multiple physical servers fail simultaneously is extremely unlikely. And, even in such cirucumstances only part of your environment would be offline. A good (and inexpensive) backup solution like BackupAssist can perform a full backup (bare metal) of physical servers for rapid restore.

    Virtualisation is not the answer in every situation.
    Why would I need a replacement server? Environment would be down as long as it takes HP to get here and fix it
    If the worst happens we have a new server onsite next day and Veeam does its stuff.
    And in the words of the Headteacher, in the event of a short downtime "we'll cope".
    I'll trade the downtime we haven't had in the 6 years we have run this setup for the numerous benefits.

    Virtualisation may not be the answer to every situation, but you don't understand every situation. I'm not worried.
    Last edited by sparkeh; 3rd February 2014 at 10:34 AM.

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  3. #47

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    Thank you all for a lot of further useful information.

    I am near certain we will go for local storage. Keeping things simple for one. Also not sure our current network infrastructure is fast or reliable enough to use for remote storage. Seemless automatic failover is I think not a requirement - recovery can I think wait for us to get another VM booted up.

    Quote Originally Posted by tmcd35 View Post
    DC2 currently sitting at 1.5Gb. DC3 using a bit more at 2.7Gb out of 12Gb (physical server, old VM host). 6Gb would be over kill, and 1 core is more than fine. I have VM's running on 1 core and 1Gb and others up at 4 core and 12Gb Ram. It's about matching the work load requirements. The best place to start is to look at the spec's and performance data from your existing machines.
    The memory usage figures are really helpful. Can you say where you get the figures from? When I look into memory measurement, I keep running into complications such as software using more memory if more is available.
    Last edited by Jollity; 3rd February 2014 at 10:47 AM. Reason: typo

  4. #48

    tmcd35's Avatar
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    Quote Originally Posted by Jollity View Post
    Can you say where you get the figures from? When I have looked into memory measurement, I keep running into complications such as software using more memory if more is available.
    Crude - Just sat watching Task Manager for a few minutes. Soon get an idea of a servers load capacity. If software (SQL) is hogging all available RAM regardless, go back to the manufacturers recommended spec's, then take an educated guess as to whether or not you think the work load in your environment would need a little more.

    IMHO, always run SQL server in a VM, and always run it on it's own. That way you can control and restrict it's memory creep and stop it from effecting any other roles.

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    Like everyone else here, I can't recommend Virtualisation enough, its the dogs, it really is. We are using Server 2012 R2 HyperV. We have several things set up 2 hosts (nodes) that host everything on one San with cluster fail over, these hosts (nodes) are then backed up using Hyperv replica 3. This basically replicates your online servers to an offline replica which can be brought up in the event that you loose the main online nodes or the san. I back each node up to its own replica. I have one DPM backing up the data on those Servers in those Hosts (nodes) and another DPM backing up all the Virtual servers on the 2 replicas, this gets away from the issues that can occur when using DPM to back up clustered servers. so if my main san or nodes go down I just bring up the replicas, and once the main stuff is fixed replicate the changes back and bring them up, then carry on. The other beauty of Virtualisation is snapshots (now called checkpoints in server 2012 R2) ever wanted to roll your sims server back to pre update, easy snapshot it prior to upgrade trail it , SIM has stuffed the update up?, no probs just roll it back.

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  8. #50

    seawolf's Avatar
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    Quote Originally Posted by tmcd35 View Post
    This I agree with 100%...

    ...This I don't (100%)...

    Most of this is way, way over spec'd. Remember it's a 100 seat environment. You need to do a proper cost/benefit analysis. Start buy describing the servers you need, add a bit (30% sounds good, I'd agree with that) for future expansion, then double itif running two server (add a third for three servers, etc) so if 1 server goes down the remander can take up the strain.

    I've never needed more than 3Gb in a DC and this is a 450 seat environement - DC2 currently sitting at 1.5Gb. DC3 using a bit more at 2.7Gb out of 12Gb (physical server, old VM host). 6Gb would be over kill, and 1 core is more than fine. I have VM's running on 1 core and 1Gb and others up at 4 core and 12Gb Ram. It's about matching the work load requirements. The best place to start is to look at the spec's and performance data from your existing machines.

    Like wise, while it might be good to have 2xNIC's for each network. Your infrastructure needs to support it. More NIC's = more CPU/RAM requirements for the host OS to support them. Do your switches support 802.11ad? (that said 2012 now includes some very cool NIC bonding features).
    Yes, I do realise it is a 100 seat environment - today. However, in 12-24 months time, the school may throw 100 iPads into the mix or decide to roll out a fleet or laptops. And if that happens it is going to be difficult to go back to management and say "we need to buy new servers" when you've just put new ones in a few months ago. You always have to think about potential growth and not just the current environment.

    As far as my recommendations on RAM, it does depend on your environment, but RAM is cheap. Are you really telling me that the average server should be configured with less RAM than the average laptop or desktop? 6GB is not over the top if you have a single DC. If you have two, drop it to 4GB, if you have three maybe you could get away with 3GB, but 4GB is minimum recommendation by Microsoft and VMware. As for CPU cores, you have to consider the peak CPU usage, not the average usage. Additionally, if you are using any of your VMs as backup proxies with Veeam (recommended) then they will need adequate CPU performance or your backups will suffer.

    CPU load due to NICs can be minimised through the use of 10GbE as it is a different protocol and utilises TCP offload to reduce the CPU usage. But, this also is a reason why I recommend bumping up the CPU configuration for VM Hosts. This is my experience from 7 years of virtualisation.

    Quote Originally Posted by tmcd35 View Post
    While I agree with the sentiment, the size of the environment says different. Personally I'd stick with local storage in each host server, but I think a couple of grand could buy a suitable NAS that support iSCSI with good enough speed/reliability for that environment. SAN's are rediculously expensive and I very much doubt is something you should be looking at.
    I agree, sticking with local storage in the server or DAS is recommended here. However, I do not think a couple of grand for a NAS would in any way bring acceptable results. You are going to experience high (noticeable to end user) read and write latencies, and the CPU/RAM of a $2,000 NAS is not in any way going to be able to handle the workload. First of all, you wouldn't even be able to barely buy 5-6 RAID quality (WD SE or RE) drives for that amount of money let along a decent NAS unit to hold the drives. Using consumer-grade drives will result in tears (slow performance, RAID failures due to drives dropping off, and a higher drive failure rate than expected).

    Quote Originally Posted by tmcd35 View Post
    All servers support 10GbE - it's called PCIe. Seriously, don't buy this now unless you need it. Buy it when you need it, when prices come down.
    Actually, that's not the case. PCIe comes in different widths, with single lane PCIe providing 2Gbp/s duplex bandwidth. So, a 4 lane PCIe bus will cater for 10GbE, but anything less will not. I have two older servers in use with 4 PCIe slots that do not support 10GbE. Most new servers do support it, but some lower to mid-tier servers do not.

    Quote Originally Posted by tmcd35 View Post
    I suppose the point I'm trying to make is there is a danger of over spec'ing and spending too much (or getting a project mothballed on cost), as much as there's a danger in under spec'ing.
    It is my experience that underspec'ing is done far more often for a virtualised environment than they are overspec'd. This happens much less frequently in a physical environment because it is a more familiar environment to most techs. The comments I'm seeing on here about the use of single server VM environments pretty much confirms that.

    Quote Originally Posted by tmcd35 View Post
    Other thing to bear in mind - Hyper-V pretty much requires atleast 1 physical domain controller (I'm aware 2012 R2 has "measures" to get around this particular chicken and egg, but...)
    Yes, it's still recommended to have a physical DC (AD and DNS) or some things can break if your VM servers are all offline. However, a low-end Dell server will suffice for this. We use an R210 with 4GB RAM housed in a separate building from our primary server infrastructure. This is also where I store my secondary Veeam backup server (DIY FreeNAS server using Lian Li case small flash drive for OS and 4 x Seagate Constellation drives for data. It is also small enough to carry offsite in a hurry like your QNAP. We also have off-site backups and a fireproof drive backups are stored in as well.
    Last edited by seawolf; 3rd February 2014 at 11:00 AM.

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  10. #51

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    Quote Originally Posted by sparkeh View Post
    Why would I need a replacement server? Environment would be down as long as it takes HP to get here and fix it
    If the worst happens we have a new server onsite next day and Veeam does its stuff.
    And in the words of the Headteacher, in the event of a short downtime "we'll cope".
    I'll trade the downtime we haven't had in the 6 years we have run this setup for the numerous benefits.

    Virtualisation may not be the answer to every situation, but you don't understand every situation. I'm not worried.
    No, I don't understand every situation. However, I do understand what can happen with a single server virtualised environment. It's fine until it all ends in tears.

    Now, if you say that you have no choice because of financial resources available and you couldn't afford even multiple cheap servers for a physical environment, that is one thing. You're in a tight situation and no choice is very good. Living on the edge is out of necessity.

    However, if you are saying that what you are doing is good advice for a virtualised environment - then I can state with 100% certainty it is not.

    If Jollity is in the first set of circumstances then so be it. Risky, but possibly with little choice. If that's not the case, then I want to save Jollity from making a very bad mistake.

  11. #52

    localzuk's Avatar
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    What you have to consider is the size of primary school budgets - they're nearly non-existent for things like servers. Nearly all primary schools I've come across have a single server for everything, with SIMS being on a workstation too.

    Going from 'one server to rule them all' to 'multiple servers with shared storage' is just not going to be justifiable from a primary IT tech's point of view when their head asks them why they suddenly need to go from 1 to 3 devices etc...

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    Quote Originally Posted by tmcd35 View Post
    Crude - Just sat watching Task Manager for a few minutes. Soon get an idea of a servers load capacity. If software (SQL) is hogging all available RAM regardless, go back to the manufacturers recommended spec's, then take an educated guess as to whether or not you think the work load in your environment would need a little more.

    IMHO, always run SQL server in a VM, and always run it on it's own. That way you can control and restrict it's memory creep and stop it from effecting any other roles.
    This method is not going to show you your peak CPU, RAM, or network usage on your servers. This is why it is necessary to use a performance monitoring system (perfmon or many of the 3rd party tools available) for a period of time that includes peak usage on your network to determine both the average and peak usage. It is necessary to cater for peak usage in your configurations, not average usage (unless the peak usage is due to a bug or error condition, in which case resolve that first).

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    Quote Originally Posted by localzuk View Post
    What you have to consider is the size of primary school budgets - they're nearly non-existent for things like servers. Nearly all primary schools I've come across have a single server for everything, with SIMS being on a workstation too.

    Going from 'one server to rule them all' to 'multiple servers with shared storage' is just not going to be justifiable from a primary IT tech's point of view when their head asks them why they suddenly need to go from 1 to 3 devices etc...
    That all depends on how you make your case. Solid research, detailed costings and a (business) requirements vs IT expenditures study goes along way. I have been able to triple the IT budget here in the past 5 years. The result - taking a school from a barely functioning IT network that was an incredible burden and detriment on the school's ability to make any use of technology in the classroom - to one that is taking a leading role in the region in the use of IT in the classroom by both teachers and students.

    And, if you read my comments, I'm actually recommending a small physical environment due to the cost and resource constraints small schools may have. This is a far more reliable and cost-effective solution for a school that can't afford a proper virtualised environment (at least two adequately spec'd hosts with local storage).

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    Really useful and correct information from most folk here, I do suggest you listen to Seawolf as 100% of what he has said is correct.

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    tmcd35's Avatar
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    Quote Originally Posted by seawolf View Post
    And, if you read my comments, I'm actually recommending a small physical environment due to the cost and resource constraints small schools may have. This is a far more reliable and cost-effective solution for a school that can't afford a proper virtualised environment (at least two adequately spec'd hosts with local storage).
    Quote Originally Posted by Trev_LCHS View Post
    Really useful and correct information from most folk here, I do suggest you listen to Seawolf as 100% of what he has said is correct.
    Not meaning any offense; While the advise boils down to the same - "two well spec'd servers with local storage" - the delivery, IMHO, is a little over complicated given the audience. In an ideal world I'd follow @seawolf's advise to the letter, in reality budgets and timescales tend to call for some more practical decision making.

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    sparkeh's Avatar
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    Quote Originally Posted by Trev_LCHS View Post
    Really useful and correct information from most folk here, I do suggest you listen to Seawolf as 100% of what he has said is correct.
    Course yeah, can't fault the techicals and in an ideal world we would all be doing that, but we don't live in an ideal world eh?
    Quote Originally Posted by seawolf View Post
    I have been able to triple the IT budget here in the past 5 years.
    That's awesome and I am happy for you. I take it you live and work in Australia? Things are very different in the UK. Would be interesting to have a show of hands to see how many UK schools have tripled their IT budget recently, I think we would have a lot of empty air.

    If I had the money to do things the way I wanted, things would be very different. I am just trying to live in the reality of IT in primary schools here.

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    Quote Originally Posted by sparkeh View Post
    Would be interesting to have a show of hands to see how many UK schools have tripled their IT budget recently, I think we would have a lot of empty air.
    I ask for triple the amount I'm allocated each year if that counts? - (side note, I actually have a meeting with the SLT after half term to talk about restructuring ICT (read - double the budget); they are currently discussing staff cuts...)

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    Quote Originally Posted by sparkeh View Post
    Course yeah, can't fault the techicals and in an ideal world we would all be doing that, but we don't live in an ideal world eh?

    That's awesome and I am happy for you. I take it you live and work in Australia? Things are very different in the UK. Would be interesting to have a show of hands to see how many UK schools have tripled their IT budget recently, I think we would have a lot of empty air.

    If I had the money to do things the way I wanted, things would be very different. I am just trying to live in the reality of IT in primary schools here.
    Yes, I am in Australia and I certainly understand most schools won't manage to convince management to triple their budget in 5 years. However, it is likely that most IT deparements in most schools will be able to increase their budget if they go about it properly. Doing your homework and then actually asking for more money with good reasons why surprisingly often results in - getting more money. It does little good to do this after the budgets have all been decided for the year, but until they are...

    If a school is faced with no choice due to budgetary constraints that's one thing, but a risky infrastructure build is still a risky infrastructure build. As I said originally, virtualisation is not always the answer, budget constraints or not.
    Last edited by seawolf; 3rd February 2014 at 11:51 AM.

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    if it helps anyone, we have a company here that sells off second hand kit, this kit is pretty good, for example they have some HP dl 380 G5's with 40 Gb of Ram dual processor for less than hundred quid, they have allsorts at different times, very happy to give details. I know its second hand kit, but i have used it for several years and it is reliable, buy it and put it under contract repair, this works for me. I have even fitted some Primary schools for around £600 with a solution that's ok for 3 years. Not right for everyone but an option.
    Last edited by Trev_LCHS; 3rd February 2014 at 11:51 AM.



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