[Novalug] best hard disk setup for home file server?

[Richard Ertel]

in light of the current problems i am having with my home file server,
i want to reconsider my choice for how i configured hard disks in my
server.

as said before, i currently have two 1.5 TB drives and two 1.0 TB
drives, all standard 3.5" internal disks.

four 1.0 TB partitions are in RAID-5 configuration, and the remaining
two 500 GB partitions are RAID-1. these two arrays are combined via
LVM into one logical volume of 3.5 TB.

my current situation has the new brand new 1.5 TB drives dying, which
of course kills all my data. they are identical drives (seagate), same
model number, maybe same manufacturing batch. both dying at the same
time.

does anyone have any experience RAIDing external USB drives in linux?
should i expect reliability to increase if i move all 4 drives to 4
external SATA to USB enclosures (5.25" enclosures with fans)? are
these enclosures suitable for 24/7 operation? would read and write
speed suffer (all transfers are over gigabit network)?

if all those USB drives running through a USB hub to a server is ok,
then what about ditching my tower and running them all to a netbook as
a server? i've seen that argument made once before, citing built-in
ups (battery), built-in monitor, low power draw and other factors as
big benefits to a netbook as server.

or am i worrying too much and what i have on my hands is just a fluke,
and in the future i should mix drive manufacturers/models to avoid
simultaneous failure?