Weblog

Friday March 03, 2006

Driving in the San Francisco Bay Area

This has been a long time coming, but where do all the drivers here get their licenses and who lets them drive?

Half of the drivers here don't seem to understand that indicators are to be used while driving, not just when stationary in the emergency lane. The really disconcerting part of this is when they fail to use them to change lanes on a freeway, you're never really sure if they know you're there or not, or if they're deliberately sliding over into your lane or just getting ready to slam into the wall by the side of the road!

As if this weren't bad enough, there are too many drivers that don't know how to enter a freeway. I've seen drivers "stop" at the bottom of an on-ramp and wait for a gap to merge into the traffic. Instructors of drivers and people doing driving tests should be making a point of people knowing that when possible, you should try to match the speed of the traffic on the freeway when it is time to merge. Yes, it isn't always possible, but it is a heck of a lot easier but does require you to look at the freeway traffic coming in your direction before you get to the actual join. Is that too hard?

Unfortunately I suspect that a large number of the "freeway merge" problems in SFBA are highway 101 specific. Why? It has too many exits and entrances and they're too close together. So much so that it's almost not either a highway or a freeway but just a major road without traffic lights. Cloverleafs, on ramps, off ramps, freeway joins and sometimes both happening all within a few hundred yards of each other. Add to this a whole lot of cars trying to go every which way and there you have it.

ZFS on our internal server

This week we've seen ZFS being deployed on our internal server, jurassic, for the first time and it is being used in a rather revolutionary manner - or at least revolutionary for Unix. Rather than having a "home directory" filesystem, we have a "home directory pool" and each user has a home directory that is a filesystem within that pool.

The first "big change" that comes about, as an ordinary user, is when you do "df". Now, rather than seeing a dozen or so lines of output there is quite a few more....over 2,000. Does this mean I no longer type "df" to casually see how much disk space is being used/free, filesystems are mounted, etc?

So what are the benefits from adopting this model? If, in the case of home directories, a systems administrator had the ability to delegate ownership of the a ZFS filesystem to a user, the user can then potentially control whether or not their data is encrypted on disk, compressed on disk, and any number of other characteristics.

Another very obvious benefit is you no longer have to do "du ~foo" to see home much space foo is using in their home directory as it is immediately accessible via "df ~foo". Finding the largest consumers of disk space is now a relatively quick and trivial task of sorting df output!