XFS and barriers

Lately at work, we’ve been trying to figure out what the deal with barriers are, either for XFS or EXT3, the two filesystems we like most. If you don’t know what barriers are, go and read a bit on the XFS FAQ. Short story, XFS comes with barriers enabled by default, EXT3 does not. Barriers make your system a lot more secure to data corruption, but it degrades performance a lot.

Tricks to diagnose processes blocked on strong I/O in linux

There’s one aspect of the Linux kernel and the GNU operating system and related tools in which it might be lacking behind, specially with kernel 2.4 series. I’m talking about I/O accounting or how to know what’s going on with the hard disk or other devices which are used to write and read data. The thing is that Linux provides you with a few tools with which you can tell what’s going on with the box and its set of disks.

Installing From Source, The Easy Way

Installing software in any unix-like operating system these days has become very easy. Package managers such as dpkg, the one used by Debian or Ubuntu, take most of the hassle by dealing with all the dependencies and intricacies that modern software has nowadays. It’s just a matter of getting the package that some hard-working and/or generous developer has made and install it in our system. It’s straightforward compared with how things were a mere few years ago.

Modifying a live linux kernel

Before reading this, I just need to say something: I’ve no idea of linux, I’ve no idea of programming, I’ve no idea of computers… Everything you read here might have been invented, so, please, do not reproduce what I write here. If you do, bear in mind that you do it under your own responsibility. In fact, what is a computer anyway? The other day we were having issues with a box that was used as a NFS box among other things.

How to monitor packets from a remote interface in real time

I was trying to debug a connection to the internet that should be controlled by tc, the tool linux uses to do traffic shaping. The scenario is this: All outbound traffic through one interface using a specific IP port should not block the rest of the traffic. Some other ports and protocols are given priority (ie: interactive traffic using ssh) But it was failing. tc is quite complicated to get it properly working.

Guadalinex 2005

So, finally, the new guadalinex is going to be made by emergya, the company I worked for last year. It”s going to be made in association with some other companies: Yaco, Interactors and, also, Canonical, the creators of the Ubuntu linux distribution, on which the new guadalinex is going to be based on. Good luck to them! ‘