Archive for October, 2008

It Shalt Not Happen

Saturday, October 25th, 2008

Citing the MySQL documentation (emphasis added):

Stage 4: Very difficult repair

You should reach this stage only if the .frm description file has also crashed. That should never happen, because the description file is not changed after the table is created:

And why do they document it in the first place? Because, sometimes, it does happen. Doh!

No Connection With This Kernel [Update]

Wednesday, October 22nd, 2008

On Tuesday I wanted to establish a VPN connection into the university network, but it didn’t work. A quick search on Launchpad revealed, that this was a bug in a recent upgrade to NetworkManager. The downstream maintainer said, one could either use the NetworkManager packages from the personal package archive of the downstream NetworkManager team or upgrade to Intrepid. I wanted to upgrade to Intrepid anyway, so why not now?
I backed up my home directory on an external hard disk and downloaded the Ubuntu alternative installer (64 bit version). Unfortunately, the first CD I had burned was corrupted. The second one was fine. Installation went ok. It didn’t find my network card, because of the e1000e issue, but as this was fixed in a recent Ubuntu kernel, I opted for a network-less installation.
Ater installation I downloaded the kernel packages for the recent 2.6.27.7 kernel, which has a fix for the e1000e issue, and transferred the files to my notebook via the external hard disk (Note to myself: Get a USB stick!). It was a bit strange to download packages for the architecture amd64 (as you can see from the e1000e thing, I’m on an Intel stack). Installation of the new kernel was successful and lsmod revealed, that the e1000e module was loaded.
Unfortunately, there still was no internet access. After some debugging, I found out that ping worked to all sites, but connections in Firefox or lynx only worked for the local network. Any attempt to connect to the outside net would just time out. By searching on Launchpad for ping works I found bug 11721. It turns out to be a slight incompatibility between the TCP/IP stack of my veteran Netgear router and that of the 2.6.27 kernel. Luckily, there is already a patch and there also is an easy workaround. Open a terminal and type in the following (you need root access to the machine):

  1. sudo su -
  2. echo 0 > /proc/sys/net/ipv4/tcp_sack
  3. exit

It’s really sack, not stack as you might think.

Update: After further investigation upstream, there is now a better workaround for this issue. Please refer to the detailed description of the workaround at the Mandriva community wiki.

All that’s left to do for me now is transferring the rest of my home directory and installing some additional software packages.