Ubuntu’s UUID schizophrenia

Ubuntu Linux

Actually it was more like I was losing my mind, not my Ubuntu…

But let’s start from the beginning… I have two identical 250GB hard disks so I’ve decided to create a RAID array out of them. Not a system (bootable) one as I had too much trouble setting it up (I’ve set it up but dist-upgrade broke it all too nicely; kernel panic, etc.). I’ve set up a separate 5GB system partition on the first drive, leaving the rest for RAID. This left me with 5GB of free space to spare on the second drive. Smart as I was, I decided to clone the system partition from first drive to the second one, using dd, so I’d still be able to boot if either of the drives crashed. I called it semi-RAID built-by-hand and, well, I was quite proud of it. All seemed fine as months passed (and remember, that this was a server and as such almost did not require any reboots). But time passed and suddenly there was the new Ubuntu out, the Feisty one, so I decided it was time to upgrade. As I had some minor troubles during the upgrade (obsolete packages, invalid config files that I ordered to keep, etc.), I was rebooting every few minutes. And this is where fun comes in…

After a successful upgrade to 7.04 the screen greeted me with a 6.04 prompt. Hmm… strange. Let’s see what’s going on. Okey, so this upgrade actually did go so well. No problem, let’s do it again. This time I did not reboot, but kept making other changes. At some point I had to reboot, though. Now I was scratching my head really hard. Some packages, I knew I had uninstalled previously, kept coming back. I was making changes to various config files only to see those changes not being written to the disk after rebooting. Like, WTF? Now I was rebooting like crazy… losing my mind more with every reboot. I was making directories like THIS-IS-FIRST-HARD-DISK-FOR-SURE only to see them disappear and reappear a couple of reboots later. I was almost crying with despair. I’ve came up with the idea to compare /dev/sda1 with /dev/sdb1. Funny thing, they turned out to be the same. Who knew, maybe my RAID-by-hand automatically turned into a real one?

I had dark thoughts. I was thinking about giving up on having two identical hard disks inside one PC and maybe about downgrading to Edgy, not even knowing whether that was possible. I was even thinking about giving up on those two 250GB disks. I was really desperate. I knew, I needed a break.

10 minutes and one glass of cold water later I was on the mission to find out what is exactly wrong with my Ubuntu. Or my PC. Or my hard disks. Or the world around me.

It wasn’t easy. The df command reported my system being on /dev/sda1. Mounting /dev/sdb1 did not help as it has been showing me the same partition. But then came the bright idea to try and mount /dev/sda1, despite it being already mounted. To my surprise it turned out to be a completely another partition! The lost one! The one I missed so much. I was in heaven, so I started googling, because by that time I just knew it had something to do with those weird UUIDs. And I’d found out that I was not alone. I was so happy…

Now I know that my mistake was to make the exact clone of the system partition and have those two partitions (with the same UUIDs, yeah, unique ids my ass) available at the same time. No wonder my Ubuntu felt schizophrenic, but it still does not justify all of this weird behavior I was greeted with. Some error, some syslog entry, anything would be helpful… is that too much to ask?

What I was left with after I’ve figured it all out was this nice free disk space report (notice the double /dev/sda1 entry):

$ df
Filesystem  1K-blocks     Used  Available  Use% Monuted on
/dev/sda1     5162796  1650512    3250028   34% /
/dev/sda1     5162796  1558632    3341908   33% /mnt/disk-a

The root of the problem is that I base most of my core linux knowledge on the RedHat from the 90s when /dev/hda1 was saint and meant exactly what it represented, namely the first partition of the first hard disk (presumably connected using the first cable and set as master). With UUIDs all this has changed. Apparently for the better, but leaving some folks like me scratching their heads with disbelief.

Yes, Ubuntu is Linux for human beings. Apparently not for all…

PS: For future reference, remember to set the UUID after doing any partition duplication using dd. You do it like this:

tune2fs -U random /dev/sdb1

Yet another anti-PHP rant

I’m quite surprised to see this great stir in the blogosphere caused by Tim Bray and his essay On PHP. I mean, what’s the deal anyway? We all know that PHP is a lousy programming language. So instead on focusing on the big picture and trying to list as many of its faults as I can remember, I’ll stay on one specific problem, which is really a pain for me.

I’ve been programming in PHP for the past five years (I’ve started using it in the beginning of 2001, during my Computer Science studies). PHP is (was?) both my love and hate. My biggest complain about it, and probably about all other programming languages used for web development, is that there is no decent way of producing HTML code from your application. No matter how hard you try, you’ll always end up having spaghetti either in your HTML or in PHP code (or even worse, in both places). Sure, separating business from presentation logic is a common practice which helps the cause (apart from the fact that most PHP folks mix HTML with PHP whenever and wherever they can). Problem is, that it’s not good enough.

It would be all much simpler if you didn’t need to put any logic into your presentation code. The moment you introduce loops or conditionals – bam – you either get unreadable code or spaghetti HTML with way too much whitespace (or without any whitespace at all) and improper indentation. Not to mention that I am probably not the only one sick of typing all those nasty angle brackets all the time. But what about all that specialized templating engines? Frankly, they are not any better. Besides the fact that some of them require a certain overhead (like defining the variables you wish to use in your templates – Smarty, anyone?), they all still carry the same burden – they either produce spaghetti HTML or have spaghetti templates.

Actually, Rails, being my current weapon of choice, is no better in this area. My .rhtml templates are a complete mess. I strive to have my HTML as pretty as it can be, because (maybe strangely) I find it easier to debug if I have a nice HTML output to deal with, instead of a nice .rhtml template. Too bad that I feel utter disgust when I look at those templates. And just as Smarty is no better for PHP, Liquid and similar projects are no better for Rails. However, there is still hope, with projects like Markaby (which, unfortunately, has its own issues, check the comments).

Just a small digression, to sum all this up. Rails has solved one other, big inconvenience, namely writing your own SQL for each and every interaction with the database. Thanks to ORM provided by ActiveRecord, you don’t have to write SQL any more (at least in most of the cases; the 80/20 rule). This is one of the basic reasons that Rails is so much better than PHP. Markaby tries to do the same to HTML, what ActiveRecord did to SQL. No more those nasty < /> characters! We’ll see how (and where) it goes.

Every time GMail is down

Every time GMail is down you are reminded just how much trust you can put in online applications/services. Not much, it seems. If my professional work depended on gmail I would be losing money now. Same goes for every other online application. They’re great when they work, giving you many different possibilities, which desktop apps cannot give you. However, when something breaks and they go down, you are left alone with many problems on your head.

So now, c’mon, don’t be like that and give me my gmail back!

UPDATE: As it was expected, after a little while it’s back up again.