- it allows unattended backups to occur
- its free
- it does incremental backups
- it occurs in the background
- its got this kick-ass trippy restore interface
- its easy enough for the average Mac user to get it
So whats the problem ?
- it doesn't allow the backups it makes to be encrypted
- you can't limit how much space it'll consume (i.e. it'll consume everything, meaning you have to either have a dedicated partition or disk to make it work properly)
- if you have encrypted DMG on your file system, it'll mount it and store those unencrypted in your backup
- you can't tell it how frequently to run
- exclusion criteria are limited to file systems, not files or directories
- if you backup across the network, and you change the network interface (e.g. from WiFi to Ethernet), your backups will not transparently resume
To get around this, I decided to store Time Machine backups on a FreeBSD-based workgroup file server. I was going to use a CIFS-based Samba server, but thought that is a bit too open. Rather use Netatalk, an open-source AppleTalk and afp server implementation (it does tons more, but I'm only interested in the afp component).
It is obscurity, but access to the network is locked by a WPA2 key, user account and physical proximity (the WiFi doesn't propogate very far). That is a lot better than a drive on my desk, me thinks.
PS. You need to issue the magic command
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
to get Time Machine to see your new share as a valid destination. I also found creating the backups a pain; this blog post was very helpful.
Now to get a 802.11n WiFi access point; candidates are the Airport Extreme, a lousy, expensive and underperforming device which hardly ever works, or a Belkin Vision N1, which just looks cool (but has also gotten some rave reviews for performance).