Unraid, freeNAS

[Brian Buhrow]

	hello.  chiming in on this thread.  Another approach to backing up
large amounts of data is one I've been using for over 10 years.  My main
server has 4 disks on it, raided together with a raid5 configuration.  At
the time I built it I used 768GB disks, giving me a total storage of just
over 2.3TB of storage capacity (768 X 3 disks).  I then allocated half of
that space for backups, and partitioned the remainder for normal use.  I
then run backups of the data to the backup area, to cover human errors or
to restore old copies of files.  And, because I'm using raid5, as disks
died, I was able to replace them without a loss of data or even much down
time.  This approach is scalable using larger and larger disks, or, if you
hav more physical space, more and more disks.  I like raid5 because you
only lose one disk worth of space for the parity disk and you can lose any
one disk and still be ok.  The down side is that you need to be ready to
replace any disk at a moment's notice, since you don't want to run in
degraded mode for any length of time.  If you're paranoid, you can run
raid6, which means you only need to spend 2 disks worth of storage, but can
lose up to 2 disks simultaneously without losing any data.  The raid5 and
raid6 configurations are a bit more complicated to set up, but they let you
use your total storage capacity more efficiently and are more resilient to
different kinds of disk failures.
	Another approach, which might be easier to set up and operate, is to
use raid1 and raid5/6 simultaneously.  Use raid1 (mirroring) on some
relatively small boot disks, so you can boot from either disk and still be
good to go.  Then, use larger disks in the raid5/6 sets for data and
backups.  

	All of this can be done with off the shelf consumer hardware, using
standard linux tools, without paying too much money.


Just my 2 cents.

-thanks
-Brian