Over the last couple of weeks I have been busying myself preparing 2 servers, one to take to Australia when Gurgi-Girl and myself emigrate and one to *hopefully* leave behind in the UK temporarily to take care of existing services and reduce downtime.
I set a few standards and goals that the servers needed to meet to improve on the current setup as well as a few odd requirements for transportation to Australia.
- The servers must have the same hardware
- They need to be compact and lightweight
- More hard drive storage than the existing file servers
- Possibly find solutions to improve building a future cluster
- Spend as little as possible to achieve all of the above
The Hardware
Instead of going out to buy some nice 1U rackmount units with nice dual CPU’s, we had to keep costs to a bare minimum, so we decided to use our 2 desktop PC’s for the task… even though they are not too powerful or even built like a server - they are small, very lightweight and have matching hardware.
The slimline Dell OptiPlex GX240 PC’s we own are not high performance desktops - but are more than capable of giving us pretty decent workstations to provide internet/word processing/cluster access and even though we could not get our ATI Technologies Inc Rage 128 Pro Ultra TF graphics card to work in Linux (we use Xorg and never tried with XFree86), we had 2 pretty good 2D desktop clients to play around with.
We upgraded from the tiny 20GB hard drives in each PC to something more substantial to replace the 50GB of space we have allocated towards our current users home directories (which now have 1GB free), so we got ourselves a pair of 160GB drives.
As storage can be expanded in the future - even though the drives are IDE, we will still be using DRBD on the computers to implement a software Raid 1 device across the network and temporarily dropping our hardware Raid 5 in favor of this.
Our only concern now is the fact we are limited to 256MB of memory (as anyone running servers will know - the more memory available, the faster services like MySQL and Apache will work)… but we can upgrade this after our move to Australia.
The Software
Well, my next cluster build I would really like to make the most of Xen… So even though these machines are very limited in memory (256MB ram) - I am making the most of setting things up to begin with.
I have decided to go with using Gentoo due to the fact I can avoid any problems with TLS by compiling with the -mno-tls-direct-seg-refs CFLAGS.
My Dom0 domain handles the file system, and with 2 computers - the best way to implement this is through the use of Raid 1 across 2 nodes using DRBD then exporting the device across the network using NBD and then making it safe to use read/write on every node using OCFS2… what makes things easy, is the fact NBD and OCFS2 is available in the 2.6 kernel and can be compiled easily into a Xen ready kernel.
I am using Gentoo again for my DomU domains and I am currently testing 1 virtual server that handles LDAP and the main MySQL database and another 2 domains just for 2 running instances of Apache.
Conclusion
All this is mirrored on both computers and even though I have a severe memory shortage - I will be putting the setup online very shortly… so far tests suggest that things seem to run really well… but only time will tell and Its something that I will follow up with a HOWTO sometime after we get things up and running smoothly in Australia… until then… fingers crossed.
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