Neurotech - the weblog of Luke Reeves

More Linux stuff. I talked recently about getting two shiny new Rackspace-hosted RedHat machines. So I got the machines, configured them and gutted everything I didn’t need, got them to a stable nice configuration and migrated applications to both.

So they chugged along, serving HTTP like no tomorrow. I logged into one of them yesterday and noticed that something was chewing up a lot of CPU (not all of it, but a significant portion). It was the RedHat Network update agent. Why would this be running for hours and spinning like mad in some wacky loop?

Turns out the RPM database on the system happily corrupted the hell out of itself. Know what you do when that happens on a RedHat (or other RPM) box? You reinstall.

At least, that’s what you usually do. Luckily both systems run the exact same packages, so I copied over the RPM database and the RHN updater works again.

This RPM corruption thing has screwed me a few times in the past also, and I’ve yet to run into it with dpkg-based systems - the one time dpkg had a severe problem on my home machine was due to overheating and the filesystems mysteriously dissapearing. Other than that, I’ve never seen a hiccough from dpkg/dselect.

Enterprise is nice, kind of. I don’t like how there’s no choice in anything from RedHat though. Like for a mail transfer agent, you got qmail, that’s it. No exim, no sendmail (as if that’s a bad thing). Debian gives you the choice of any MTA you like, and in theory RedHat ES does this as well through similiar use of virtual services provided by packages. But it doesn’t quite work because there is no official Exim RPM from RedHat. Oh, and get this - once you do install Exim from source or an external package, half of the programs on the system can’t send any mail. This is really wacky - most applications send mail through the “sendmail” program, which is usually a link to the actual MTA. But Mutt, without qmail installed, can’t send mail.

And again, exactly like I was talking about Fedora, RedHat doesn’t provide any upgrades to the packages except security updates until the next update. That’s frustrating. It’s similar to Debian Stable I suppose, where they QA the packages and freeze them excepting bug fixes and security changes. But there’s a lotta bugs I’ve found so far - the Mutt/qmail is just one example.

The RPM database corruption, on the other hand, should never, ever happen. If RPM or the underlying Berkeley database is easily corruptible (and in my experience it is) then RPM should take snapshot backups of the database once a night. In fact, I plan on writing a quick script to do just that.