KVM + KSM = Big Bag of Win

Posted on September 26th, 2011 by Luke Sheldrick.
Categories: IT / Tech.
Tags: , , , , .

26 09 2011

I bought a HP Microserver a few months ago, to expand my media storage at home. HP had a promotion where you’d buy the server, and they’d give you £100 cash back. Not bad considering you can pick them up online for around £220. £29 for 8GB of DDR3 for it, and it’s quite an ample home server. I bought four 3TB disks, and have them in Raid-5 for the main storage, and I also have an E-Sata disk shelf with four more 2TB disks, also in Raid-5. The main storage array gives me around 8TB of usable storage, and the other around 5.5TB, so I have quite a bit at home to be getting on with.

A colleague at work today pointed out that HP had extended the offer until the end of September, so I thought I would pick up another one. My reasoning is they’re bloody cheap for what they are, and it’ll make HA testing in my lab a lot easier, with two identical machines.

However I decided to see actually how loaded the server was with what I run on it. The tasks that usually run on it backups of my various colos, streaming to the AppleTVs at home, transcoding up to 8 channels via the DVB cards, and downloading various media online. Well, basically, it isn’t breaking a sweat.

It’s currently running Ubuntu Server 11.04, which has pretty good support for KVM, so decided to spin up a few VMs to see how it handled it. I wasn’t overly optimistic, as AMD Turion™ II processor, which is basically designed for netbooks. However after spinning up a another Ubuntu Server instance, the server seemed to have no issue with this at all.

At that point I decided to clone the VM a couple of times, and then spin them all up to load test. 4 clones later, they all booted fine, and the box carried on with no real issues. I showed another colleague at work, and he’d asked how it would cope with Windows guests. The reason he was interested is he has just completed his MSITP qualification, and had quite a bit of difficulty running all the required server instances using his laptop and VMWare Workstation.

This evening I installed a base install of XP, and cloned that 4 times. Again, no real issues, so I decided to give every host 1G of memory (the server only has 8GB total), and see how KSM got on with the VMs. At the moment, it’s still scanning through memory pages, however it’s been running for around 20 minutes, and it’s already reclaimed 2.5GB of memory. No doubt given it some more time, it’s going to reclaim even more.

To say I am impressed by the Microserver, and KVM + KSM would be an understatement.Think I’ll setup a HA cluster when I get the other server, and see how that compares the likes of ESX.

Below just the quick setup I was playing with this evening.


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