Monday, September 17, 2007

EuroBSDCon was great, disks dying and some scary Windows stuff

This Monday finds me safely back from EuroBSDCon and trying to do useful things while the file server gets restored.

Of course it had to be that way. With me off to EuroBSDCon to do the tutorial and other refreshing geekiness, in the first batch of mail I retrieved after arriving in Copenhagen was a log summary from the machine which holds pretty much everything datadok is working on at any time, with these nuggets:

> > ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=410884031
> > ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=410912703
> > ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=410884575
> > ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=410905887
> > ad6: FAILURE - READ_DMA status=51 error=40 LBA=410857151
> > ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=446104667
> > ad6: TIMEOUT - READ_DMA retrying (1 retry left) LBA=446104667
> > ad6: TIMEOUT - READ_DMA retrying (2 retries left) LBA=522840603


This is what disks say when they've run out of space to map bad sectors into. The disk wasn't quite dead yet, but definitely time to plan a replacement. Not much to be done about that right away except alert the colleagues that there would be file server downtime on the Monday afternoon. Disks will die, and sysadmins end up with the task of replacing them.

My brief summary of EuroBSDCon is that it was an excellent conference, lots of good talks, interesting people to see and in a good, clean location with a network connectivity which worked, most of the time. update: finally my eurobsdcon pictures are on flickr

For my own part the PF tutorial went reasonably well, with 24 people signed up and I think one or two sit-ins. People were paying attention and there were a few good questions which made the session more interesting with a little more improv than the last few times I did this tutorial. Answers were had, though, and I believe a good time with useful info for the people who had signed up for the session. Not too many hours after we were done, the number of unique visitors (aka host names or addresses) to the tutorial tree since last EuroBSDCon rolled past 18,000.

After lunch Marco Zec's session about virtualizing the FreeBSD network stack was really interesting. Unfortunately none of the Thinkpads present were able to boot from the FreeBSD-current image Marco had prepared and supplied on USB thumbdrives, actually producing pretty much the same crash (illustrated here). But a very interesting topic and session. I'm glad I stuck around for it.

The Wednesday I had the choice of sightseeing, sitting in on Kirk's session and holing up in the hostel basement's hacker room to get some writing done, and I ended up going for the latter option, getting significant parts of the logging chapter done. There is of course a limit to how long you will avoid interruption in a semi-public area, but that session was certainly useful.

The EuroBSDCon hacker area with both wired and wireless networks was available to conference attendees all conference and tutorial days. Naturally it took on a social function in addition to being a convenient way to surf and fetch your email.

For the conference itself, it was sometimes hard to choose which talks to go to. I still think Ike's jails talk (pix here, here, here) was my favorite (similar but not identical to the one he gave at AsiaBSDCon in Tokyo), but there were a lot of good ones. I ended up managing to miss Pierre-Yves Ritschard's Load Balancing talk since they'd switched the schedule around. I hope there's a chance to pick up the essentials at some later date.

Fortunately Wim and Machtelt turned up to organize the OpenBSD booth (convenient for restocking your clothes cupboard) and some news about OpenCON - there will be an OpenCon 2007, but there's still some organizing to do. I hope to be seeing you there, Venice November 30th through December 2nd.

From the Windows Is Scary department, one episode from a few weeks back which I suddenly remembered when I realized the guy quietly hacking to the left of me was FreeBSD USB guru Hans Petter Selasky:

When I saw 4GB USB thumb drives priced at just under NOK 300 (USD 55), I decided I needed one. The drive mounted with no trouble at all in in OpenBSD (mount /dev/sd1i at the location of your choice), and I thought good, I'll just delete those .exe files to make room. A few days later I needed to retrieve som files which turned out were most easily accessible from my Windows machine at work. So I plugged in the new 4GB thumb drive.

Windows machines always do strange things and take a while to recognize new hardware, but this time it claimed to have found a new CD drive. A few confusing minutes later, with various message boxes flashing across the screen, the machine begged for a reboot. I let it have that, slightly puzzled but not entirely surprised that Windows wanted the user to jump through a few extra hoops to make something work.

I was able to retrieve the files eventually, while trying to avoid yet another quirky Windows application which wanted to handle my files. As it turns out, the device actually emulates a CD drive as well as USB mass storage. Here's what it looks like in /var/log/messages on my OpenBSD laptop:

Sep 17 22:23:23 thingy /bsd: umass0: SanDisk Corporation U3
Cruzer Micro, rev 2.00/0.10, addr 2
Sep 17 22:23:23 thingy /bsd: umass0: using SCSI over Bulk-Only
Sep 17 22:23:23 thingy /bsd: scsibus2 at umass0: 2 targets
Sep 17 22:23:23 thingy /bsd: sd1 at scsibus2 targ 1 lun 0:
SCSI2 0/direct removable
Sep 17 22:23:23 thingy /bsd: sd1: 3913MB, 498 cyl, 255 head,
63 sec, 512 bytes/sec, 8015502 sec total
Sep 17 22:23:23 thingy /bsd: cd1 at scsibus2 targ 1 lun 1:
SCSI2 5/cdrom removable

The reason all the strange and scary things happened with the Windows machine is that the emulated CD contains Windows Autorun files, which it seems there is no easy way to turn off or is at least enabled by default in that operating system. What I find slightly disturbing is that, as Hans Petter explained, this behavior is part of the device's firmware and you can't get rid of that five or six megabytes of useless software in these devices. The best you can do is use a system which ignores such silliness.

Returning to the file server, the box is a few years old and has by now probably had most of the original components replaced. The last time we replaced the motherboard, we were still thinking that SCSI was the only way to go for storage, disks and tape both. Not too long after that, we decided that actually SATA was OK for that little office of ours, but when the time came to replace that disk, I discovered that actually the motherboard had only two SATA ports on it, one for the system disk and one for the dying data disk. So copying across from one SATA disk to another had to be done via Ethernet instead. Fortunately installing a useful operating system takes only about twenty minutes, and the some tens of gigabytes transferred while I was writing this article. Far faster than restoring the same data via rsync from our offline backup, though.

Among the things announced in Copenhagen were that there will be an AsiaBSDCon in March 2008, NYCBSDCon will maybe be next year in the fall, and the next EuroBSDCon will be in Strasbourg. I hope to be at several of those, time and money allowing. But now on to finish that book.

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