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I just got a new laptop with a 25Gb ssd and I was wondering which would be best if putting my home directory (minus music and videos) there or and arch install (minus pacman pkg cache). I read the ssd related article in the wiki and even though it mentions some optimizations and considerations it doesn't mention anything regarding this issue.

Realistically, you're going to want to stick as much data that's read/written as you can on your SSD - one of the big things SSDs excel at is random reading and writing, and even consumer SSDs today have write lifes that'll generally exceed the life of the host hardware (heck, that's been true for a long while, but "optimizers" gonna "optimize"). Just remember to look at TRIM support and the pros/cons of mounting with discard vs running a scheduled fstrim; I wouldn't suggest doing things like disabling the journal. Media and other such large-sequential-io type stuff can still go on a separate HD, of course. Question though: where in the heck did you get a 25 GB SSD in a new laptop in this day and age - or was it 256?