A couple of thoughts:

Of any File system I've used in recent years, ext4 is the _only_ one that has caused me 
data loss.  And serious data loss.  I've used either the older reiser, or XFS, on big 
drives for backup stuff without any issue.  Not sure what the current crop of "good" file 
systems are... but I've never considered ext4 one of them since it failed its most basic 
functions for me.

If these drives will be travelling about - I would encrypt the entire drive partition with 
something like truecrypt (or whatever current supported encryption scheme is out there... 
shame what happened to truecrypt...) - and then put your file system of choice inside that.

If the drive is lost / stolen, it will just appear as an unformatted disk.
Dan





On 09/04/2015 04:40 PM, Mike Miller wrote:
> I have the impression that zfs is a safer and more reliable system than ext4, so maybe I 
> should want zfs, but is it working on Linux?  Is it hard to get it installed for use 
> with an external drive?
>
> I guess $0.06/GB-month is a good deal if you have a small amount of data to backup.
>
> Mike
>