Older blog entries for berend (starting at number 362)

Was running on Ubuntu 9.10 for a long time, and very happy with that. But one must move on I suppose, so had a bit of downtime yesterday and decided to upgrade to 10.10. Ubuntu upgrades always went fantastic, never had a problem, but this time it was a nightmare. Had upgraded a couple machines already, but not yet my main machine.

First upgraded to 10.04, the LTS release. Everything went OK, until I booted. When it came up, the nvidia driver didn't load, so into low res graphics mode. Weird. Booted on an older kernel, that went OK. As I had to upgrade to 10.10 anyway, I didn't bother to pursue it. And somehow I got the idea that I should do the upgrade from the latest kernel, so I booted back into the latest kernel with low res graphics. But I think the problem was that this kernel didn't support my Lenovo W700 well, so the kernel simply didn't work and that's why nvidia didn't load.

I could start the upgrade to 10.10 fine, no issues there. But about half way X window/machine/kernel crashed. Could no longer boot.

On Windows this would have been a reinstall, but luckily on Ubuntu you have options. So I downloaded the Ubuntu 10.10 live CD, booted from that, and then chrooted to my disk. With liberal use of "apt-get upgrade", "dpkg --configure -a", etc. and several retries I somehow was able to finish the upgrade and install the 10.10 kernel, which worked fine.

System still in a somewhat bad state though. mysql wasn't installed, so had to do that myself. Bit of a problem as well as my my.cnf had statements in it that prevented it to start. Starting it gave me all kinds of warnings that I needed to upgrade.

Lost my Thunderbird profiles, currently loading them from a backup tape.

And then of course we have the usual and expected: PHP upgraded to 5.3 which will cause issues. I'm first trying to see if I can resolve them, before going back to 5.2. For example SimpleTest doesn't work anymore, but the latest trunk fixes this.

Recently I experiencing a 2s to 3s lag with Skype calls. Finally found out why. This is what you see when you have this lag:

$ pacmd list-sink-inputs | egrep '(current|requested)'
current latency: 2004.02 ms
requested latency: 66.00 ms

The solution is to remove loading the module-suspend-on- idle in /etc/pulse/default.pa.

Had a really weird issue with:

sieveshell localhost

core dump would follow. So I tried to debug this by putting print statements to see what function would fail. That brought me deep into the bowels of Cyrus IMAP and next into Cyrus SASL.

In the end the final function that failed was gss_init_sec_context() which appeared to be a FreeBSD function. And that finally gave me a Google search on the the problem. It's a very long thread, but the solution is here.

Another would be to disable gss.

Not sure if Jeremy Chadwick's patch is already accepted, because, if not, with the next cvsup the problem will come back.

Michael Brandon is trying to get links for quadracentifiable. Good luck with that Michael!

Source upgrade from FreeBSD 6.4-STABLE to FreeBSD 8.1-STABLE completed. Only one issue though:

ad2: 152627MB <WDC WD1600BB-00GUA0 08.02D08> at
ata1-master UDMA100
GEOM: ad2: geometry does not match label (81h,63s !=
16h,63s).

This appears to be a harmless message and can supposedly be fixed with:

bsdlabel -e -A /dev/ad2

And it did. After manually fixing the heads, I could mount it. Ran an fsck:

fsck /dev/ad2e

to make sure nothing was screwed, and it wasn't.

Just finished reading a very beautiful article in CACM July 1010: x86-TSO: A Rigorous and Usable Programmer's Model for x86 Multiprocessors.

Very useful, very clear semantics.

Very weird issue. I was on the Vodafone NZ Red network and had set my MTU to 1492 as that supposedly is the optimal size for pppoa. I had to switch to the Vodafone wholesale network in order to get ownership of my phone number so I could transfer it to a voip system.

After the transfer I had very weird connection issues, for example https would only work up to a point, i.e. I could make the ssl connection, send the HTTP request, but the response would never arrive. Or ssh to a server, but when I typed ls the reply would never come back.

Ultimately my issues are described here. MTU Path Discovery is broken. I suspect Vodafone's wholesale network might be blocking things, but don't know for sure. Could be my firewall for all I know. When I change the MTU on the clients to 1492 everything works. But that's annoying, so set the MTU on the modem back to 1500.

Another weird thing on Linux is that I can't do MTU Path discovery. For example:

ping -s 10000 www.dslreports.com

works fine. Setting the DF bit:

ping -M do -s 1472 www.dslreports.com

gives me the biggest packet I can sent. Which I don't really understand because as I understood it the biggest packet on ppoa is slightly smaller, i.e. 1478. But I suppose with ATM cells they just carry the MTU and don't care what the real limit is.

Anyway, drove me crazy for hours.

Installing pfSense on a Gigabit motherboard. Core dump with ohci_add_done. Seems to have been present since 7.0 and this is FreeBSD 7.2. Not nice. You have to unplug the USB keyboard and then FreeBSD will boot.

Had an issue with OpenOffice 3 not wanting to open files on an nfs mounted drive. It appeared that my FreeBSD NFS server wasn't running the lock and stat daemons. After that it was perfect.

Still having trouble with my new firewall rules. Sometimes web pages take a long time to load (up to a minute), just looks like connections open very slowly or packets travel slowly.

Not sure what this is. Have no increased my network buffers and max sockets, which did help with my network speed. I can now transfer 20MB/s on my Gigabyte lan. Far short from the supposed 100MB/s I should get, I know. But currently don't have the time to figure out why I don't get that speed.

Also played with turning off net.inet.ip.dummynet.io_fast, that might have effect as well. Currently it's on again, so let's see how it behaves. Those intermittent lags are quite noticeable: you click on a link, and nothing happens, so let's see if I get that today or not.

Maybe I should upgrade to FreeBSD 8 as I'm still on FreeBSD 6.4. Could do in-kernel nat as well.

Our school also needs better internet, so I'm thinking of deploying a pfsense box with a cheap ADSL modem. I could do traffic shaping with lowest bandwidth for the students and higher priority for staff and voip. And of course have Squid, so browsing experience should become much better.