The best distributed filesystem for home directories
I'm looking for the best distributed filesystem to share my home directory among all my computers, and I'm interested in what advice I could get here.
Here are my requirements:
1) It must be completely POSIX compliant, because I've noticed that many programs will break if not.
1a) Must support file locking (i.e. flock()) preferably sharing lock advisories between the clients
1b) Must support hard links, and be able to recognize a hard link connection by looking at the number of references
2) It must have encryption, and security suitable for it to be exposed to the internet.
2a) I would like to use password-less authentication. Preferably SSL client certs (HTTPS style). Static keys (SSH style) are also fine. I would begrudgingly accept a password authenticated system if it used a fairly secure challenge/response algorithm if it met all of my other requirements. (Extra points if it supports PKCS#11 and thus supports smart cards)
2b) Encrypted traffic must be an option.
2c) No thanks to kerberos. It was too annoying to maintain when I tried it before and I don't like passwords.
3) Preferably, it should be stable and fairly easy to maintain.
4) Optionally, it should be tolerant of network drops, and reconnect automatically as needed, because my laptop wireless is a little flaky sometimes.
Thanks to everyone in advance for your opinions and recommendations!