SSD, II

Volume 14, Issue 53; 21 Dec 2011

Some thoughts on successfully configuring a working dual-drive system.

Last weekend, following my utter failure the previous weekend, I returned to the problem of configuring my laptop to have two drives: an SSD along side its original spinning rust.

There's no clear evidence that doing so will significantly decrease the amount of time that my regular “big compile” takes, I just don't like to lose.

On my first attempt, I started with the idea that I'd make the whole thing transparent by mounting the spinning rust bits on top of the SSD in various places. That didn't work for a couple of reasons. I fell back to using symbolic links to fake it. That doesn't really work either. Before long, I'd tangled myself up so completely that I just pulled the rip cord and restored from backup.

The second time around, I started with less ambitious goals. I accepted the fact that I wouldn't be able to make the new configuration transparent. I planned to configure the machine so that I could boot off the SSD and login with no dependencies on the spinning rust.

I run very few things “on startup”. After I'm logged in, the first thing I run is a “start.mac” script that loads a bunch of stuff that one might configure to start automatically. My feeling is, if I'm rebooting, it's likely as not because something has gone wrong and I want the machine to do as little as possible before it stops and let's me take over. I reboot so infrequently that the extra step required doesn't bother me.

Having accepted those terms, I tried to limit the number of symbolic links created. No mapping /projects→/Volumes/Data/projects, etc. As I find scripts and configurations that depend on /projects and other changed locations, I update them to point explicitly to the new locations.

I do have a few symbolic links, mostly to satisfy programs that think they know where data should be or as a convenience to point to directories that contain large amounts of data (for cryin' out loud, there's 10Gb of data under ~/Music/iTunes and don't get me started about ~/Library/Application Support/Steam).

All and all, it's now running quite smoothly. As Jacek mentioned in a comment on the previous post, the most noticable speed increase is in the little things. Booting is almost instantaneous. Even big applications start in a second or two. The machine is quieter too, which is nice. The spinning rust spins down when it's not in use and the SSD of course is utterly silent.

I don't mind being an outlier, and I like to tinker, so I think it was worth it, but it's not the sort of thing I could recommend to everyone.