Nice! Is there a maximum number of connected usb-sticks for the "master-usb-host-controller" of the motherboard? How many usb sticks would you guys suggest to put together? 1*2*4*8 = 64 16GB Usb-Sticks for about 1TB with high performance access times? The cheapest sticks I have seen until now were at the market for about 1 Euro per Gigabyte, e.g. the Kingston DataTraveler, isnt that a bit expensive, paying 1000 Euro (= 1361 USD) for this Terabyte?
On Mon, 2010-02-22 at 10:02 +0100, Frank A. Stevenson wrote: > On Mon, 2010-02-22 at 07:11 +0100, sascha wrote: > > > The access time for 4 usb sticks is already 0.3ms. Their combined size is > > 64GB. Take 32 of these groups and you get down to 0.01ms (if it scales > > indeed). > > What i was able to test was that it scales up to 16 devices. I got 0.08ms > > access time with this configuration IIRC. > > Even if you need 2 or even 4 distinct USB host adaptors to connect 128 > > devices, you still end up faster and cheaper than with SSD. > > Besides that, those PCIe SSDs are still more expensive than 2.5inch SSDs. > > And we certainly do not need hundreds of megabytes per second bandwidth. > > The write performance is also of no concern. > > > > As for the optimization of the USB bus, that comes for free. If you start > > 4 CPU threads and manage to make each thread access the data blocks of > > a single device, then the access time improvements scale linearly with the > > number of devices. > > Nice! It seems that USB mass storage should have us well covered for 5K > requests a seconds :-) I did some further experiments on a single stick, > and got access times down to 0.4ms when accessing the block device > directly. (Which means we do away with the filesystem altogether.) > > I added the test code to svn: > tmto-svn/tinkering/various/speedy.cpp > > typically you have to do "sudo time ./speedy /dev/sdX" and get timing > figures for 10000 random reads. (Just under 4 seconds in my test) > > F > > > > _______________________________________________ > A51 mailing list > [email protected] > http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51 _______________________________________________ A51 mailing list [email protected] http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51
