[plug] USB RAID

[Craig Ringer]

On Fri, 2004-04-23 at 15:07, Adrian Woodley wrote:
> I have a WD 200Gb HD ATA100 with 8Mb of cache in a USB2.0 tray. It
> performs only slightly worse than a similar spec (8Mb cache, ATA 100)
> drive inside the computer.

I'm really surprised to hear that. Seek times should be OK, but I'd
expect a significant performance hit when (say) unpacking a large
tarball. You _are_ using DMA, 32bit IO, etc on your internal disk(s)
right?

> If I was gonna build the office server again I would definitely go for
> RAID 5 over several USB HDs. 

A lot of people swear by FireWire for that purpose, because FireWire
disk access tends to use a _lot_ less CPU time (like the difference
between SCSI and PIO IDE), and FireWire hubs work really well when
embedded into external disk cages.

Of course, SATA2 looks like the way to go for this eventually, as it has
nice external cables and connectors, longer cable runs, etc.

Craig Ringer