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Showing posts from June, 2010

Btrfs or how to lose space

On the linux-btrfs mailinglist there was an interesting entry about internal fragmentation in btrfs.

A basic test brought up many questions about the btrfs filesystem design. Btrfs is a filesystem that uses the b-tree algorithm. There has been a debate if it is a good idea to use b-trees for filesystems.

I'm not enough into algorithms, but I let you decide...

The test consists of a loop, creating as much 2k sized files as possible on a 1GB Filesystem:

# for i in $(seq 1000000); \ do dd if=/dev/zero of=/mnt/file_$i bs=2048 count=1; done (terminated after getting "No space left on device" reports).
The result from Edward Shishkin (RedHat) was 59480 Files. This would give us 2048*59480 ~ 116MB. Or in other words, we would waste around 880MB of Space.

In the meanwhile, Chris Mason, inventor of btrfs created a patch for increased utilisation.

He was able to achieve 106894 Files. That's 208 MB or a waste of 800MB. I'm not sure what he meant by the comment about the dup…

Real-Time visualization of Spamhaus with Splunk

Static visualization is boring :-)

This time I've run the same search in real-time...

Spamhaus Blacklist visualized with Splunk

Image
I was interested in how the Spamhaus blacklist works, so I ran a Splunk search for 5 Minutes and generated a map with the results.

Every dot is at least one IP-Address listed (high probability of an infected machine). Impressive...

(Click to enlarge...)