This tutorial was helpful. The white balance was fixed, exposure was 100 ISO, and focus was at infinity. I might want to try a closer focus next time; see if that changes things.
The University of Michigan does not offer support for mounting ITS AFS space from non-university machines. I was able to set it up after a bit, and thought I’d document it here in the hopes that it’s helpful. For Ubuntu, the packages are
openafs-krb5. The realm name is
UMICH.EDU – case matters. Next, as the official docs say: run
kinit <username>, (assuming your local username differs from your uniqname) which will prompt for your password, followed by
aklog. You should now be authenticated as yourself with your home directory at
/afs/umich.edu/user/<username first letter>/<username second letter>/<username>/.
It seems clear in retrospect that my Windows installation died due to a failing hard drive; I RMA’d it after the self-test reported read failures. I hope to build a RAID array at some point, but it’s somewhat out of my price range currently to buy a couple of drives.
College costs too much – when I talk to people who went to college in the 70s, they tell me how they were able to pay for college with a part-time job. What happened?!
I’m trying to figure out if over the summer (hopefully as part of GSOC!) I could write a filesharing application for Freenet – one that would make Freenet about as easy as Vuze to find and download stuff. User interface would be incredibly important in this effort, as features are not sufficient for – and too often impede – intuitiveness. My target audience is people who aren’t computer-savvy. I’d want to use a lot of jQuery to make it more like a desktop application. When I made my chat plugin using Toadlets it was somewhat of a pain so I hope I can avoid having to do that somehow. I also need to learn more about and implement proper Model-View-Controller separation. Freenet itself doesn’t really have this. :\ Perhaps I could use WoT and allow people to publish a list of keys to associate with an identity. The tool should make it easy to assemble and update these lists, and people could share keys to the lists (likely USKs?) outside of the application-offered channel (ex Freemail) in order to have secret lists.
I’ve discovered collectd, which is a pretty comprehensive logging daemon. I’m using the ping plugin to attempt to get some data on when (and hopefully why) the Internet connection here in the apartments starts being worse than usual. The graphs aren’t incredibly clear, and it’s not as simple as lots of packet loss anymore – even so, TF2/Counter-Strike can be unplayable, especially later at night. I’m pinging the gateway on the other side of the DSL connection, as well as a few servers around the US. I wonder if the spikes later on are what’s causing the problem, but I don’t know if that’s due to more network load from us or in general.
My classes are interesting, but I have enough work that I feel like I’m always behind. I like political science though – questions such as what the role of government is in free speech, or what free speech is fascinate me.
I find that among my least favorite types of problems are those that I’m unable to learn from. My main system drive was spontaneously remounted read-only, and upon Alt-Sysreq-reisub’ing, the OS didn’t come up and I got “error: partition not found” and a grub rescue> prompt that couldn’t do anything; not even “help.” I pushed in all the SATA cables and it came up, but upon reboot the drives were out of correct boot order. Bizarre. The part about this that scares me is that I’m for the most part unable to learn anything from this, and I wasn’t able to do anything to stop it from happening again because I don’t know why it happened. The same thing applies to the mysterious times this machine goes completely unresponsive while idle or suddenly doesn’t have video on boot, then spontaneously regains it. The former has happened a few times, the latter only one.
From programming in assembly, I finally realize how segmentation faults are really nice compared to the alternative. Data and instruction separation is a luxury. Miss a bounds check and suddenly you’re executing things not intended to be instructions and you get really weird opcodes and the whole thing dies. It can get really frustrating.
I realized the only reasons my server has gone down at dad’s are due to external forces: either the power has gone out at the power outage or circuit breaker level, or cables have been unplugged by unwitting family members. I wonder how much better colos are. ChunkHost was really nice, and I’d have likely continued once my “free beta” ended (I have my suspicions it’s a marketing thing for “free trial”) if I had more disposable income to the point where I felt I could justify a monthly fee.
EDIT: I had forgotten the time it went down as I was upgrading from Debian Lenny to Squeeze. I had set up a virtual machine for fallback, but I didn’t end up using it: in restoring the VM from backup I unknowingly uncovered a configuration problem with one of the hosted sites that showed up a few days later on the main server. Whoops.
Gather ’round children, and I’ll tell you a tale of what happened to a Linux box when its sole filesystem was remounted read-only due to disk errors. This coincided with the backup server being taken offline with an errant circuit breaker.
I first became aware of something rotten in the state of Webserver when the sites hosted on it became messes of PHP errors in place of content. I could
ssh in, but after entering my password I was greeted with:
-bash: /etc/profile: Input/output error
-bash: /home/steve/.profile: Input/output error
That was a scary greeting.
ssh continued running, but PHP died, commands other than Bash builtins refused to run, and Bash profiles failed to load. I don’t know if some of this is due to damage or the partition being read-only. I’m pretty sure that commands expect
/var/lock to be writable. I now have those mounted as
tmpfs as per the instructions on the Arch wiki here. The warning about
lighttpd seems to not apply in my case.
cURL seemed to run at first but died when I tried to do anything with it. I had hoped to POST files over, as
sftp would not run.
su still worked. Tunneling worked too, so I was able to still access other machines behind the firewall through the server even though I couldn’t run
ssh from the machine itself. I ended up using
cat to copy over text files. For binary files I had to get a great deal more creative. The only way I could interact with the server was over
ssh; the server was an hour away and even if I did have physical access,
mount refused to run (unable to write to
/etc/mtab?) and I was afraid that the files I could access might be only buffered in memory and that rebooting into a LiveCD/USB would lose them. My options were limited. I had to use only Bash builtins to pull binary files off the server in text form. I modified a version of this hexdump script to pull files over
| tee file.log to avoid having to copy-paste.
tee takes output from
stdout and redirects it to
stdout and a file given as an argument. Here’s the script:
while read -s -u 3 -d '' -r -n 1 char
printf "%02x" "'$char"
I lacked a text editor and couldn't write to anything on the root filesystem. I found a
tmpfs mount point (I used
/dev/shm would also work.) and stored the file by
echoing the script line-by-line. In retrospect, I could have used
\n and the
-e (interpret backslash escapes) option to do it in one line:
echo -e "exec 3<\"\$1\"\nwhile read -s -u 3 -d '' -r -n 1 char\ndo\nprintf \"%02x\" \"'\$char\"\ndone" > scriptfile. I ran it with
bash scriptfile target_file.
All of this effort, though fun, ended up being unneeded as I had forgotten about my set-and-forget backups. Hooray
mysqldump nightly and let
rdiff-backup handle any differences. I restored it on the new machine with
source mysql_dump.sql on a
mysqladmin prompt, but as it contained users and privileges things got messy as the
debian-sys-maint accounts were partially overwritten. I used
mysqladmin to sort out the
root password confusion and
phpmyadmin to replace the
debian-sys-maint password with the one found (in plaintext?!) in
It was a fun puzzle even though it was ill-timed.
The Wolverine Soft 48-hour game competition revealed to me just how difficult physics engines are to make. I spent two days coding and recoding collision resolution only to get different sets of bizarre, game-breaking glitches. At least collision detection was easy because everything was a circle. It was fun and I'd like to do it again. Maybe I should become familiar with a physics library such as Bullet and ask for it to be approved for use in the competition. The guideline is unless it's an approved library, all code and assets (with exceptions for music and sound effects) must be created primarily on-site within the 48-hours. Next time I'll have to plan to do homework in advance. Ignoring homework for a weekend is inadvisable.
I am currently taking 17 credits, and the time management is very difficult, though has not yet proven to be entirely impossible. I'm considering taking classes at LCC this summer to lighten the load during the next school year. I applied to Camp CAEN to be a counselor, but they emailed back saying camp was ending due to the director retiring. The odd part is their website, as of this writing, has no mention of it that I can find. I'll have to see if I can get an internship over the summer.
The power outage made for a very interesting problem. I had inadvertently broken PHP by turning on compression in php.ini when apparently I wasn’t supposed to. This was back when I was trying to get the WordPress compression working. I didn’t know PHP’s configuration wasn’t working until the server was forced to reboot due to the power outage. The initial problem was that the server was not set to turn back on automatically after power loss, which I had set intentionally fearing damage if it attempted to turn on during a brownout, but perhaps I should enable that ability. Even once it turned on, after a fsck (over 330 or so days of uptime I think) it hanged on setting the clock and needed a hard reboot, which necessitated that I go over to the server physically and reboot it. Before this I set the DNS entries to my dad’s house so that I could display an explanation of what had happened, and I changed my password for my DNS service as it had gone too long without being reset, and subsequently forgot to correct it in the call to the update script. I managed to get the DNS fixed, then I found PHP was broken, then in the course of my attempts to fix that, lighttpd refused to start at all. I was unaware that I could only declare one error.log, so it appeared that it was not giving any error output, but it was writing to the last error log I had declared, and I was checking the wrong one. Thanks to incredible help from the folk in #lighttpd on freenode, it’s working again.
In other events, I set up Skype on my Grandma’s machine, and I hope she finds it useful. I’ve been working on Breakout in AP Comp Sci and physics collision is interesting, but I think if I end up making a game I’ll be using a physics library for sure. MIT didn’t accept me, as I anticipated. I’ll be going to University of Michigan, but I still have work to do and forms to fill out on the way.
The site was down due to a power outage. I took the downtime as an opportunity to move the shelving the machines are on a foot or two away from the wall so I can get to the back of them. One of the zombies’ networking didn’t come up properly, even with a /etc/init.d/networking stop and restart, but upon reboot it worked correctly. I wish I knew the underlying cause of that.