On my Debian Linux system during the install I decided to use disk encryption (the one offered during a regulard Debian install). When the system boots up I need to enter a password and then the "real" boot begins.

Could someone explain how this encryption is performed? Does it happen before or after the filesystem's laid out? Can I use any filesystem available for Linux with the disk encryption?

The */etc/mtab/* is more complicated than what I was used with Linux and I take it it's related to disk encryption but I'm really not sure. Here's (what I think is) the relevant bits from my */etc/mtab*:

```
/dev/sda1 /boot ext2 rw,relatime,errors=continue 0 
/dev/mapper/archon-root / ext4 rw,noatime,errors=remount-ro,user_xattr,commit=300,barrier=1,data=ordered 0 0
rootfs / rootfs rw 0 0

```

I don't really understand why /boot is ext2 and why / is ext-4 and using a */dev/mapper*.

Could /boot be itself using ext4?

Could / be using, say, ZFS and yet still offer encryption?