ZFS

So ZFS is all shiny and stuff. We'll be using it for disk based storage of backups for the following reasons:

• All data (and metadata) can be validated with cryptographically strong hashes
• Data deduplication

Released versions of ZFSonLinux do not work on the kernels I'm running (3.12.x from backports.org), so I'm playing with zfs-fuse instead.

So, here's the first annoying thing I've come across. The ZFS tools go off and automatically mount filesystems in your just-created pool. And they go and make directories to mount those filesystems on. Quite annoying. What's wrong with putting entries in /etc/fstab and typing mkdir /foo? Instead zfs pool create solarissucksballs ... will create a /solarissucksballs directory on your machine and mount the new pool's filesystem there. I'm sure this behavior comes from Solaris, but I find it quite obnoxious.

Some useful tidbits

• zfs set checksum=sha256 poolname # changes a filesystem's data integrity check algorithm from the default Fletcher4 to SHA256.
• zfs set dedup=sha256,verify poolname # enable dedupe, use SHA256 hashes as keys, but also do a bit-by-bit comparison before deciding two blocks are the same
• zfs set canmount=noauto poolname_OR_fsname # gets rid of the obnoxious /etc/fstab-less mounting behaviour at ZFS start time.