First up then, a series of basic copy functions. Demos are downloaded from Xbox Live as one large file, almost like an ISO or ZIP, containing the myriad smaller files. Straight copy tests from the Xbox 360 HDD onto the flash device should give us some idea of the maximum throughput capable, and also better inform us about the differences of various flash media.
For the purposes of the test, the Forza Motorsport 3 demo (1,337,663,488 bytes, or 1275.7MB, or 1.247GB) was used. First, to test write speeds of the drive, the demo was copied from HDD to USB.
Write Speed Test: Copy Forza 3 Demo from HDD
|Drive Tested||Time Taken||Average Speed|
|2GB Forza Stick||02:37.5||8.09MB/s|
|4GB Sandisk Cruzer Blade||04:46.1||4.46MB/s|
|8GB MicroSD Card||05:15.5||4.05MB/s|
|40GB USB HDD||01:23.3||15.31MB/s|
|128GB Samsung SSD||01:21.7||15.61MB/s|
So, some interesting conclusions here. Firstly, it's fairly obvious to say that not all USB flash drives are created equal. At the lower end of the market, 3-4MB/s write speeds are commonplace. Sometimes slower even. While reading speeds are generally higher, some might say there's little point buying a bargain basement 16GB drive if it's literally going to take you hours to fill it: even our preferred ByteStor drive takes a good 40 minutes to fill to capacity.
Secondly, we clearly have a bandwidth ceiling in effect here. While read/write speeds vary on a mechanical hard drive as it fills up, our completely blank 40GB PS3 drive is definitely capable of writing speeds well in excess of a paltry 15.31MB/s. Similarly, the SSD used can manage a sustain 60MB/s of throughput, so we can say with some degree of certainty that bandwidth via the 360's USB interface tops out at around 16MB/s or thereabouts.
There's far less of a gap between read performance on our hardware, as this table demonstrates:
Read Speed Test - Copy Forza 3 Demo to HDD
|Drive Tested||Time Taken||Average Speed|
|2GB Forza Stick||01:24.1||15.16MB/s|
|4GB Sandisk Cruzer Blade||01:34.0||13.57MB/s|
|8GB MicroSD Card||05:20.5||3.98MB/s|
|40GB USB HDD||01:22.5||15.46MB/s|
|128GB Samsung SSD||01:19.3||16.08MB/s|
Probably the biggest shock is that the 16GB ByteStor drive outperformed the SSD! There's another benchmark later on where another device marginally beats the SSD, and there are two potential explanations here. Firstly, that the USB controller in the enclosure the SSD resides in probably isn't that great. However, more likely is the fact that the top-end throughput of the Xbox 360's USB interface itself seems to vary. We found that running the same benchmark three times on the same drive could see different results, usually with a variance of around a second, but anything up to three seconds.
The next conclusion is fairly stark. Boy, despite passing the Xbox 360's internal performance checks, the MicroSD card is sloth-like not only in terms of write performance, but also when it comes to reading too at around 4MB/s each way. Fine for a storage option designed for a mobile phone, but not great for use with Xbox 360.
Finally, our specifically chosen champion of USB, the 16GB ByteStor drive, performs reasonably in writing but works like an absolute winner when it comes to reading. The reason we chose this drive is that it was identified as a very cheap means to provide a storage option that challenges the capabilities of the original 20GB hard drive that came with the launch Xbox 360 deluxe packs, and while its write performance is only adequate, we identified it as potentially being a better all-round performer than the actual HDD the 360 shipped with.
Before the testing continues into our next chosen application, we decided to put the USB interface through its toughest workout yet. We copied the Forza demo from the ByteStor drive with its excellent read performance, onto the SSD. The notion here was to see how throughput decreased with two devices in play simultaneously. The result? Two minutes, seven seconds, meaning a 10.04MB/s throughput rate meaning a bandwidth cap even when multiple devices are in play.
Now to put the cat amongst the pigeons. The USB storage option on 360 is fully featured. You can copy your save games onto flash, you can move your profile onto a fully mobile device that'll work anywhere, and yes, you can install games too. The challenge, first of all, was to find a game that would install onto all of our drives.