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Thinking of completely rearranging

Community Veteran
Posts: 1,236
Registered: 02-08-2007

Thinking of completely rearranging

I am thinking of completely changeing my network later in the year.
Currently my 3 main computers:
Desktop: AMD Quad core 4GB Ram
Windows Server AMD 2ghz 1Gb Ram
Linux Server: Pentium 2.4Ghz 1Gb Ram.
I am playing with Xen and I am thinking of combining my 2 servers to free up a box for Freenas. Due to electricity prices I will never run more than 2 physical servers.
My proposed layout would be:
Desktop: Pentium 2.4Ghz 1Gb Ram. (I use XP and don't play games or edit video. I think the quad core is completely wasted here. I would upgrade soon after though.)
AMD Quad Core 4Gb Ram: Xen virtual host for Windows and Linux servers. (And any future servers. This motherboard supports up to 8Gb of Ram)
AMD 2Ghz 1Gb Ram: Freenas box with almost all of my existing disks to serve all other machines including the virtual servers.
The reason for this is because we use Xen in work and I have really started to like the idea of it. With the new layout I would be in a position to expand greatly with servers and storage over time.
I know the obvious disadvantages of this being that a hardware failure woulds cause more problems  but is there any other advantages/disadvantages I should be thinking about.
12 REPLIES
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Thinking of completely rearranging

Not that I'm an expert but I can't see anything particularly dangerous there - but hopefully Barry will get a look at this thread and offer his sage advice soon too Smiley
It might be worth having a look at ESX if you're going for a box that's totally dedicated to virtual hosts but I guess if you're already used to Xen then little point - but a quad core with 4GB of ram will run quite a lot Cheesy
Sounds like a sensible plan to me.
Community Veteran
Posts: 3,789
Registered: 08-06-2007

Re: Thinking of completely rearranging

Xen is awesome Smiley
Make sure that your motherboard and processor support the AMD-V extensions (may need turning on in the BIOS) otherwise you won't be able to run Windows in a Xen VM.
We run several XenServer hosts here, and get almost bare-metal performance out of them.  You can get the full XenServer distro for free direct from Citrix, including XenCenter which makes 99% of administration very easy.
If you're looking at hosting drives via iSCSI or NFS, FreeNAS is a good option, (although my personal preference is towards OpenFiler, mainly due to more exposure with it).  It may also be worthwhile investing in a second NIC for the Xen host and the iSCSI host, and running a crossover cable between the two just to run the storage over.  This segregates "storage" traffic away from your network, and means that the response times for the virtual disks will be constant, and not dependant on your normal network traffic.
Xenserver requires a 16GB disk to install to, (although with an installation tweak you can drop that down to a 4GB disk for the latest 5.6 release), so you could look at a very small SSD.
For the FreeNAS/OpenFiler box, I would recommend either RAID6, or RAID50 depending on the number of compatible sized disks that you have.    This should give you the best performance.
Hope that gives some useful info!
Cheers
B.
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Thinking of completely rearranging

Ok thank you for the tips.
My processor does support the AMD-V extensions as I have successfully now got it working. I am replying now on the virtual XP pro machine via RDP and it is very impressive. I wouldnt otherwise know it was not a physical computer.
I didn't realize than Xen came as its own distro. I will have to look into this. I am currently running it on a CentS host.
I do have experience with Freenas so that was my prefrence but I may have a play with open filer. Network cards are cheap so I was going to use at least 2 in the host anyway.
I will be putting  lot of thought into the setup of the file server. I am working on a budget and wll be using mostly existing disks rangeing from 80 to 200Gb in size. Not sure how this will end up affecting my RAID options.
Much more testing will be done before I make any permenant changes and probably not until after the holidays as I have quite a bit of media to remove to disc from the existing servers before I can start changing disk layouts.
Community Veteran
Posts: 3,789
Registered: 08-06-2007

Re: Thinking of completely rearranging

XenServer is a Citrix-created Xen distribution, loosely based on CentOS. 
The main reason for suggesting it is XenCenter, which is brilliant for administering Xen, and steers you away from the xe commands (which can be fairly archaic!) 
Using various sized disks in RAID can be problematic.  Generally, it will only create a raid-stripe based on the smallest capacity disk that you have, (unless you use JBOD which has no resilience, it's merely striping the volume across all disks).
For example, if you had an 80GB disk, a 500GB disk and a 1TB disk, the maximum RAID5 partition that you could create would be 160GB (80 + 80 + parity 80)
However, you could create a 500GB RAID1  "mirror" across the 500GB and the 1TB disk
OpenFiler (and probably FreeNAS) can use 'md' to create varying stripe-size RAID arrays, but it can get really complicated!
Multiple NICs will only be useful if you are connecting to disparate networks (such as a storage link and a data link as I suggested), or you have a switch that supports some form of link aggregation (802.3ad, or LAG/LACP for example).
If you have an aggregation-capable switch (highly unlikely unless you happen to have a corporate switch lying around!) then you can bond multiple distinct NIC links into one "fat pipe" into the network. There are downsides though - for example all traffic between two distinct hosts can only pass over one physical link.  Link Aggregation is generally used to hook a high-capacity file server (or Xen server) into a network, serving multiple clients.
We use Xenserver here for hosting various server tasks, including two fairly heavyweight loadbalancers for our storage.  The Xen hosts that the loadbalancers run on each have two quad-port Intel NICs in them, which are bonded into pairs of ports and then hooked into seperate VLANs on our corporate network.
HTH
B.
matt_2k34
Grafter
Posts: 1,300
Registered: 09-07-2007

Re: Thinking of completely rearranging

Few limitations of ESXi 4.

  • You have to format all drives in their proprietry format *spit*

  • Maximum Drive size of 500gb for a RAW drive (you can connect drives which arent in their format, however this limit can be a pain (but not necessarily for you Smiley )


I did use ESXi, but then found these limits, got annoyed and just put WinServer back on, on its own.. Rather a waste of spec too...
*goes to look up Xen*
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Thinking of completely rearranging

Firstly Matt I did try an install of ESXi and got a BSOD somewhere along the way so I ditched that very quickly.
I am now completely sold on Xen as it was my preference from the start. Try the Xen live CD, runs on Debian Lenny, you too will also be convinced. Grin
Barry, I wish I had the money and the justification for much of what you have mentioned but unfortunately it is really only a home network.
I will definitely be looking at XenServer since you mentioned that it is loosly based on CentOS, my server distro of choice and what I am currently using.
Based on the disks I have I was thinking of 2 seperate RAID 1 arrays. I don't need a great deal of storage or performance, just to provide some redundancy for digital photographs etc. I currently have a RAID 1 array in each of the 2 existing physical machines.
I have read several pros and cons for hardware vs software raid. I much prefer the software (md) option provided in Linux over hardware raid. Other than controller failure is there any other good reasons to use hardware raid over software raid provided by Linux?
My main aim is to create a position where I am easily able to change/add servers and storage in the future if needed. I am limited with the current physical server setup.
My existing Linux server has 2 NIC's. This acts as a firewall to block DHCP passing between the 2 sites on the network (a friends house) connected via wireless bridge. The new host machine will require 2 cards as it will also need to provide this role.
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Thinking of completely rearranging

Thank you Barry for pointing out XenServer and XenCenter. Fantastic. So simple and so lightweight compared to using a full Linux host running Xen.
This is definitely one of the coolest free bits of software I have ever used!
matt_2k34
Grafter
Posts: 1,300
Registered: 09-07-2007

Re: Thinking of completely rearranging

with xen could i..
have 1x 160gb hdd with the hypervisor on (and guest OS's)
Connect at least 5 NTFS Formatted Drives, then access them in a Windows Guest OS ?
also is it usable, or Linux user only?  as id like to use the hypervisor to learn linux...(as a guest OS) so once its set up i can tinker.. but i dont want to try setting it up, getting confused and lost ?  Grin
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Thinking of completely rearranging

Barry is clearly the man to answer your questions about XenServer as I have only started with it but I will say that XenServer is very easy to set up. Then you install XenCenter on a seperate Windows desktop to administer the virtul host. This too is a really simple and useful interface. It can be installed by simply visiting the IP of your XenServer machine in your web browser. .net Framework SP1 is needed.
I will say that XenServer is just that, a server. It is designed for use on a remote machine.  It has no desktop option but it is not needed. It is really also designed for setting up virtual servers and not desktops. The XenCenter does have a viever to see the desktop of your virtual machines but it is pretty poor in performance. If you do require desktop access like in the case of a Windows VM then RDP or VNC is much better once your VM is installed.
15 minutes and you will be ready to start installing virtual machines, Windows, Linux or otherwise.
Are you thinking of learning Linux to use as a server? If so I personally would recommend CentOS. Linux is not as scary as you may think. You can use control panels etc. to help run your machine.  Virtualmin/Webmin is fantastic and has a really simple automated install script available from the website.
There are 3 main things when starting with Linux (coming from Windows) that I noticed.
The way Linux mounts drives is completely diferent and better once you get used to it. Linux does not use drive letters like you will be used to.
File permissions can cause you so many problems if you are not used to way Linux handles them.
If you read up about the above you will be in a better position to start playing with Linux.
The last thing is the Desktop. Impossible from a Windows point of view to imaging using a computer with no desktop but if you are using Linux as a server there is absolutely no need for a desktop. The Gnome or KDE desktops available with most versions of Linux provide little or no administration options especially when it comes to server tasks. They were not designed for this purpose. You use the command line or a good control panel like Virtualmin/Webmin as I mentioned above.
There is plenty of help available and although you will get very frustrated during the learning process, you will grow to love Linux and soon realize that it is a much better server operating system than Windows could ever be.
matt_2k34
Grafter
Posts: 1,300
Registered: 09-07-2007

Re: Thinking of completely rearranging

Yeah its a remote machine, atm i RemoteDesktop to the machine in question... im assuming it would be similar to just use the XenCenter (as in, will give me my windows OS as if i was sat infront of it?)
i understand Linux doesnt usually have a desktop, but i dont particularly want to do anything just by commandline, i remember you talking about webmin before too - so would be worth a look.... id still like a desktop to 'fall back on' for more menial tasks.
possible for the Guest OS to be accessed directly by remote desktop? (e.g. giving the Host its own internal IP ? - im sure this is how ESXi does things)

Specs of Server:
Intel Q6600, 2.4Ghz
6gb Ram
3.8TB Storage over 6 HDDs
Running Windows Server 2008 64bit.
i think i can use the resources much smarter Smiley
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Thinking of completely rearranging

The Viewer in XenCenter is pretty poor in performance. You would just use that while installing Windows or Linux.
Yes, you can use RDP as normal once Windows is installed. The host wil have its own internal IP but so will each of your virtual machines. When installing Windows or Linux as a VM just give it an IP as you normally would. XenServer bridges the physical ethernet card with all the IP's of your virtual machines.
So you could have:
192.168.0.10 XenSever host machine
192.168.0.11 Windows Virtual machine
192.168.0.12 Linux Virtual Machine
etc etc.
I have found that when using RDP I cannot even tell that the Windows machine is virtual.
You will need to try and loose the "Windows" frame of mind when it comes to a desktop, LoL. In Linux there is no point having a desktop to "fall back on". As I have mentioned the desktops provide little or no useful tools for administring a server.
Basically it is just how it Windows and Linux are built. Windows is built entirely around a desktop whereas Linux is not. A desktop in Linux is just an optional extra for anyone who is using it as a desktop machine.
Every Linux tutorial you find on the internet is based on the command line so sooner or later you will have to learn a bit.
There is a small piece of software called Putty(SSH client) which is good for connecting to the command line of your remote Linux Machine
Webmin will do almost everything you will need to look after the server without using the comand line apart from to install it in the first place.
You can install Webmin by itself which will look after the server but I would advise installing Virtualmin which is basically a hosting control panel and also includes Webmin. The reason for this is because it has a simple install script which does everyting including installing all the other software you may want to play with, Apache Webserver, BIND Dns server, Postfix mail server, MYSql etc.
I think the specs of your machine should be more than good enough for the job. You could probably run 20 VM's on that without issue. Remember when installing a Linux VM (without Desktop) you only need to allocate about half the memory you would for a Windows VM doing the same job.
Unfortunately I only hve one quad core machine, my current desktop which I am forfiting for use as my host. So I will then be using an old single core P4 as my desktop (current Linux server) at least until I buy new hardware.
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Thinking of completely rearranging

It turns out things are not a straight forward as I first thought. I currently have an APC UPS connected to my physical Windows server via serial cable aswell as a shared USB printer. I thought I could access those ports on the host from within the a VM by editing a simple config file but from what I have read this is not possible.
As far as I can see I have the following options:
Use CantOS as the host with ZEN installed.
Use a stand alone print server or some kind of USB network server and USB to serial cable for the UPS.