[Ltsp-discuss] VMware resource requirements for hosting thin clients?

[Mike Cammilleri]

So LTSP memory/processing requirements can vary widely depending on your environment and what your users are doing with it. I get that. But I was wondering if someone really had a finer sense on what the requirements are for the following situation.


A virtual machine running Ubuntu 14.04 LTS and ltsp-server and dhcp on VMware Server with hardware thin-clients booting to it. The LTSP server virtual machine has two NICs. One for the network we image it with and the 2nd being the thin-client network that dishes out the ip addresses. I have the default gateway set to the NIC that's public facing, so in theory all thin-client sessions are getting their network traffic through that NIC.


What should I set for the specs on this LTSP server VM for X number of thin clients? Same as the hardware requirements listed in the LTSP Installation Guide? Users should only be web browsing, document editing, they may play some audio, basic every day stuff. How will this saturate the virtual NIC?


I have maybe 100 concurrent users so clearly I need either.....


1. Multiple LTSP servers running across multiple VM's in VMware. I separate thin clients in dhcp so that only one LTSP server answers them on boot. Thus dividing the users among VMs. But how much does this tax the VMware Server host machine?


2. Have one LTSP VM server in Vmware and make it HUGE, basically one of the only few VMs on the host. Possibly purchase a VMware host machine just to run one or two or three LTSP servers that have really beefy settings. How will the network traffic perform?


3. Given option two, having a large LTSP server run as a VM for many users doesn't really buy me much if I have to have such a beefy VMware host. Might as well just stick with hardware/bare metal machine for my LTSP server with no virtualization.


It's all a question of scaling but gets complicated when considering virtualization.


I think it comes down to which is a better scheduler? VMware or Ubuntu? If VMware better utilizes the host resources for the LTSP Server VM and the strain the clients put on it, then sure, maybe we'll dedicate one of our VMware hosts just to this task. But if Ubuntu is a better resource scheduler than VMware then might as well just stick with installing Ubuntu directly on the machine and skip any virtualization.


Thoughts? Am I nuts? Who else is doing this and what have you found? It's hard to test with 4 concurrent sessions right now.


--mike

[Jeff Siddall]

On 03/02/2016 03:00 PM, Mike Cammilleri wrote:
> So LTSP memory/processing requirements can vary widely depending on your
> environment and what your users are doing with it. I get that. But I was
> wondering if someone really had a finer sense on what the requirements
> are for the following situation.

Sorry, but I don't have an answer for something of your scale. I run at
most 30 concurrent users, many are kiosks and only get used intermittently.

However, my modest 4 core CPU and 8 GB RAM server handles that easily.
That said it doesn't take many runaway processes (Adobe and Mozilla I am
looking at you) to suck up those 4 cores.

Also of concern is the NIC. One full screen video stream can easily eat
up 500+ Mbps so only two users watching videos means a saturated 1 Gbps
NIC. Consider putting clients on throttled ports (ex: 10/100 Mbps
ports) or going with 10 Gbps NICs or maybe just blocking access to
obvious resource intensive sites.

Audio is less bad but still significant as each stereo 48 kHz stream is
a couple of Mbps.

So under "normal" load you might get 100 users on a modest server, but
you need to be very diligent about monitoring for resource hogs.

> I think it comes down to which is a better scheduler? VMware or Ubuntu?
> If VMware better utilizes the host resources for the LTSP Server VM and
> the strain the clients put on it, then sure, maybe we'll dedicate one of
> our VMware hosts just to this task. But if Ubuntu is a better resource
> scheduler than VMware then might as well just stick with installing
> Ubuntu directly on the machine and skip any virtualization.

That one is easy: a hypervisor will never give you better performance
than the bare metal server. Period. VMs are for flexibility not
performance. If you don't need to easily move your LTSP server to
different hardware, or share the host resources among multiple guests
then you don't need a VM infrastructure.

That said I am currently working on moving my LTSP server to a KVM guest
primarily for reasons of resiliency. If I run into any issues I will
simply put it back on bare metal.

Jeff

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[Johan Kragsterman]

Hi!


-----Jeff Siddall <***@siddall.name> skrev: -----
Till: ltsp-***@lists.sourceforge.net
Från: Jeff Siddall <***@siddall.name>
Datum: 2016-03-03 16:25
Ärende: Re: [Ltsp-discuss] VMware resource requirements for hosting thin clients?

On 03/02/2016 03:00 PM, Mike Cammilleri wrote:
> So LTSP memory/processing requirements can vary widely depending on your
> environment and what your users are doing with it. I get that. But I was
> wondering if someone really had a finer sense on what the requirements
> are for the following situation.

Sorry, but I don't have an answer for something of your scale.  I run at
most 30 concurrent users, many are kiosks and only get used intermittently.

However, my modest 4 core CPU and 8 GB RAM server handles that easily.
That said it doesn't take many runaway processes (Adobe and Mozilla I am
looking at you) to suck up those 4 cores.

Also of concern is the NIC.  One full screen video stream can easily eat
up 500+ Mbps so only two users watching videos means a saturated 1 Gbps
NIC.  Consider putting clients on throttled ports (ex: 10/100 Mbps
ports) or going with 10 Gbps NICs or maybe just blocking access to
obvious resource intensive sites.

Audio is less bad but still significant as each stereo 48 kHz stream is
a couple of Mbps.

So under "normal" load you might get 100 users on a modest server, but
you need to be very diligent about monitoring for resource hogs.

> I think it comes down to which is a better scheduler? VMware or Ubuntu?
> If VMware better utilizes the host resources for the LTSP Server VM and
> the strain the clients put on it, then sure, maybe we'll dedicate one of
> our VMware hosts just to this task. But if Ubuntu is a better resource
> scheduler than VMware then might as well just stick with installing
> Ubuntu directly on the machine and skip any virtualization.

That one is easy: a hypervisor will never give you better performance
than the bare metal server.  Period.  VMs are for flexibility not
performance.  If you don't need to easily move your LTSP server to
different hardware, or share the host resources among multiple guests
then you don't need a VM infrastructure.

That said I am currently working on moving my LTSP server to a KVM guest
primarily for reasons of resiliency.  If I run into any issues I will
simply put it back on bare metal.

Jeff





There is a huge difference in the requirements for the server between running fat or thin clients. I don't really see the meaning with running thin clients anymore, since the hardware that works splendid with fat clients getting so cheap.

At home I run Ubuntu/LTSP as a KVM virtual machine on OmniOS(Illumos dist), which give me ZFS in the bottom. I do it for resiliency and manageability reasons, and because I like OmniOS, as well as I like to have a VM infrastructure at hand. I got a lot of other stuff running on that machine in zones or in VM's.

If you run fat clients, you don't need to pass through the server, you don't even need it to deliver /home if you don't want, you can get that from another nfs server if you like.

You can add your users from LDAP, either to the server or directly to your fat clients(with some hack). With fat clients you don't need to bother about any nic's, you just see to you got a backbone that support your needs.

The fat client H/W I use is some asus mobo with a quad core celeron, and 8 GB ram in a very small chenbro chassi. Running 64-bit img. I believe costs/client is like $250. It is very fast and has excellent graphics! Lst time I rebooted the OmniOS server was about 6 months ago. The LTSP VM I rebooted about 2 months ago.

Regards Johan



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For additional LTSP help,   try #ltsp channel on irc.freenode.net




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[Mike Cammilleri]

Thanks Jeff, the idea of throttling the ports the thin-clients are connected to is a good one and one that I have not thought of. Most students I catch watching YouTube arent doing so in full screen but you never know.

The other issue is the CPU resources only because I'm sharing with other VM guests. Having the LTSP server on a VM host does give me the flexibility of deploying more LTSP servers and dividing users among them more easily - but would be ideal if I did not share the host CPU resources with other guests that are doing other non-LTSP things.

Bare metal is more simple - but rebuilds or expansion is a bit more tricky - and less "green". I'm adding more users to my test VM LTSP server every day and I'm noticing most issues being with CPU intensive apps. Has anyone modified the links to apps in the Applications menu to launch applications on other servers? That would be ideal.

--mike

________________________________________
From: Johan Kragsterman <***@capvert.se>
Sent: Thursday, March 3, 2016 10:47 AM
To: ltsp-***@lists.sourceforge.net
Subject: [Ltsp-discuss] Ang: Re: VMware resource requirements for hosting thin clients?

Hi!


-----Jeff Siddall <***@siddall.name> skrev: -----
Till: ltsp-***@lists.sourceforge.net
Från: Jeff Siddall <***@siddall.name>
Datum: 2016-03-03 16:25
Ärende: Re: [Ltsp-discuss] VMware resource requirements for hosting thin clients?

On 03/02/2016 03:00 PM, Mike Cammilleri wrote:
> So LTSP memory/processing requirements can vary widely depending on your
> environment and what your users are doing with it. I get that. But I was
> wondering if someone really had a finer sense on what the requirements
> are for the following situation.

Sorry, but I don't have an answer for something of your scale. I run at
most 30 concurrent users, many are kiosks and only get used intermittently.

However, my modest 4 core CPU and 8 GB RAM server handles that easily.
That said it doesn't take many runaway processes (Adobe and Mozilla I am
looking at you) to suck up those 4 cores.

Also of concern is the NIC. One full screen video stream can easily eat
up 500+ Mbps so only two users watching videos means a saturated 1 Gbps
NIC. Consider putting clients on throttled ports (ex: 10/100 Mbps
ports) or going with 10 Gbps NICs or maybe just blocking access to
obvious resource intensive sites.

Audio is less bad but still significant as each stereo 48 kHz stream is
a couple of Mbps.

So under "normal" load you might get 100 users on a modest server, but
you need to be very diligent about monitoring for resource hogs.

> I think it comes down to which is a better scheduler? VMware or Ubuntu?
> If VMware better utilizes the host resources for the LTSP Server VM and
> the strain the clients put on it, then sure, maybe we'll dedicate one of
> our VMware hosts just to this task. But if Ubuntu is a better resource
> scheduler than VMware then might as well just stick with installing
> Ubuntu directly on the machine and skip any virtualization.

That one is easy: a hypervisor will never give you better performance
than the bare metal server. Period. VMs are for flexibility not
performance. If you don't need to easily move your LTSP server to
different hardware, or share the host resources among multiple guests
then you don't need a VM infrastructure.

That said I am currently working on moving my LTSP server to a KVM guest
primarily for reasons of resiliency. If I run into any issues I will
simply put it back on bare metal.

Jeff





There is a huge difference in the requirements for the server between running fat or thin clients. I don't really see the meaning with running thin clients anymore, since the hardware that works splendid with fat clients getting so cheap.

At home I run Ubuntu/LTSP as a KVM virtual machine on OmniOS(Illumos dist), which give me ZFS in the bottom. I do it for resiliency and manageability reasons, and because I like OmniOS, as well as I like to have a VM infrastructure at hand. I got a lot of other stuff running on that machine in zones or in VM's.

If you run fat clients, you don't need to pass through the server, you don't even need it to deliver /home if you don't want, you can get that from another nfs server if you like.

You can add your users from LDAP, either to the server or directly to your fat clients(with some hack). With fat clients you don't need to bother about any nic's, you just see to you got a backbone that support your needs.

The fat client H/W I use is some asus mobo with a quad core celeron, and 8 GB ram in a very small chenbro chassi. Running 64-bit img. I believe costs/client is like $250. It is very fast and has excellent graphics! Lst time I rebooted the OmniOS server was about 6 months ago. The LTSP VM I rebooted about 2 months ago.

Regards Johan



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Ltsp-discuss mailing list. To un-subscribe, or change prefs, goto:
https://lists.sourceforge.net/lists/listinfo/ltsp-discuss
For additional LTSP help, try #ltsp channel on irc.freenode.net




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https://lists.sourceforge.net/lists/listinfo/ltsp-discuss
For additional LTSP help, try #ltsp channel on irc.freenode.net

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