ZFS RAID0 pool without redundancy

You likely are seeing a situation where at least one of your used disks became unavailable. This might be intermittent and resolvable, both Linux implementations (ZFS on Linux as well as zfs-fuse) seem to exhibit occasional hiccups which are easily cured by a zpool clear or a zpool export / zpool import cycle.

As for your question, yes, ZFS is perfectly capable of creating and maintaining a pool without any redundancy just by issuing something like zpool create mypool sdb sdc sdd.

But personally, I would not use ZFS just for its deduplication capabilities. Due to its architecture, ZFS deduplication will require a large amount of RAM and plenty of disk I/O for write operations. You probably will find it unsuitable for pools as large as yours as writes will be getting painfully slow. If you need deduplication, you might want to look at offline dedup implementations with a smaller memory and I/O footprint like btrfs file-level batch deduplication using bedup or block-level deduplication using dupremove: https://btrfs.wiki.kernel.org/index.php/Deduplication

This is a duplicate of: Why did rebooting cause one side of my ZFS mirror to become UNAVAIL?

In your case, the device names or symbolic links in the /dev/disk-by-* directory on your system were either not present or were renamed.

It's best to use /dev/disk-by-id devices for your zpool instead of by-path, as the path names can change. (grrrr... Ubuntu udev)

In /dev...

by-id/   by-path/ by-uuid/

So my spools look like the following (note how the devices aren't sda, sdb, etc.):

[root@BigHomie ~]# zpool status -v
  pool: vol0
 state: ONLINE
  scan: scrub repaired 0 in 0h1m with 0 errors on Sat May 24 17:14:09 2014
config:

    NAME                                            STATE     READ WRITE CKSUM
    vol0                                            ONLINE       0     0     0
      mirror-0                                      ONLINE       0     0     0
        scsi-SATA_OWC_Mercury_AccOW140403AS1321905  ONLINE       0     0     0
        scsi-SATA_OWC_Mercury_AccOW140403AS1321932  ONLINE       0     0     0
      mirror-1                                      ONLINE       0     0     0
        scsi-SATA_OWC_Mercury_AccOW140403AS1321926  ONLINE       0     0     0
        scsi-SATA_OWC_Mercury_AccOW140403AS1321922  ONLINE       0     0     0