External HDD for audio samples

[ibi sum]

The deal with the bus question is this: USB does require that the host
CPU be involved in moving data to and from the devices.  This ties the
USB host controller and your CPU together during all i/o operations
and reduces the amount of processing power your CPU has to deliver for
other things, like synthesis.  The CPU has to be involved in each
transfer between devices - one transaction to receive the data,
another to send it on to the next device.  On modern multi-Ghz CPU's
this isn't "really" a big deal .. but in the days of 400mhz CPU's and
so on, it was a bit of a concern.  You can definitely bog a WinXP
machine (fixed a little bit in Win7) by having lots of file copies
going on between disks across different USB Hubs, also - the OS has to
behave itself during these i/o operations, and for some older variants
of Windows there were definite performance hits during bulk transfers.
 There is also some care required for how you position your USB
devices on a hub - USB devices can interfere with each other a lot
easier than Firewire can, and the conditions for this interference are
quite easy to come across.

With Firewire, things can be different - the Firewire controller
hardware itself is involved in the process of shunting data between
two nodes on the Firewire bus - the CPU can be removed from the
process of transfer save for a 'check-in' function (seeing if things
are completed), and this does *not* use as much CPU.  If you get a
decent Firewire-based disk system set up, you can pretty much do
copies and i/o on those disks without having a significant impact on
CPU time.

With USB, also, it is important to realize that the more USB devices
talking on a single Hub, the more likely that collisions/contention
occurs, which needs the CPU to arbitrate.  If you design your USB
system well, however, you can drastically minimize the overall impact
this contention will have on your system - if you're on a PC that has
the slots, get a PCI->USB card *just* for your Audio devices .. MIDI
and Audio USB interfaces on one Hub, Mice/Joysticks/keyboards on
another hub, Disks and storage on another separate hub .. also, make
sure you isolate USB2 devices from USB1.1 devices, as the presence of
a 1.1 device on a Hub with other 2.0 devices degrades performance
completely .. this is a common gotcha.

In short, with modern USB2 and CPU speeds being what they are, you can
definitely use USB2-based disks in a production capacity, but you do
have to isolate things if you want the absolute best performance ..
with Firewire, its a bit easier to just set and forget, however.  My
option would always be to use Firewire instead of USB, but certainly
you can get away with USB-only.

Also, one thing about ExpressCard as an expansion option: deep down
inside, its just USB2 and PCI-E bundled together in a fancy package.
You might find yourself getting a good performance boost if you get an
ExpressCard->USB2 interface, however, as ExpressCard slots are usually
implemented as their own USB Hub, separate from the other USB Hubs in
the system - not always the case, but you can check if you get a USB
node dump tool (in Linux its quite easy to walk the USB tree in /sys
or use lsusb to do it) and count the Hub nodes.  The more there are in
your system, the better.


On 2/18/10, K9 Kai Niggemann <canine at waf80.de> wrote:
>
> On 18.02.2010, at 00:59, Joost Schuttelaar wrote:
>
>> USB will do fine. Just get a 99 USD xTB USB drive and don't look back.
>
>
> actually at the price these drives are: just get two and back up all sounds
> on a regular basis...!
>
> Kai
>
>
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