30 Nov
2012
30 Nov
'12
8:21 a.m.
I think if you really really don't care about speed then it'll be ok.
20 hours sounds about right to me considering the USB interface is CPU bound and everything is having to go through the USB Mass Storage subsystem. On a direct interface like SATA/SAS I have seen arrays of this size rebuild in a lot less time but that is to be expected.
The only other thing you might see is performance problems across the system when working this array hard, really depends on the spec of the machine it is attached to but it's going to get fairly tied up with stuff sitting in IO wait and depending on what processes that happens to it can block other things. You might be able to fix a bit of that by making sure write caching is enabled on the array.