I have two 8 board stacks of bitbury boards. One stack has 2 broken usb connectors so I run 6 USB cables to it and have the other two connected via CANBUS.
I had this stack connected to a PC running Linux and it worked pretty well (average about 370-380 GH/s for the whole stack). That Linux PC recently died though and now I have it connected to a raspberry pi using a power 7-port hub.
The raspberry pi is running rasbian and the latest cgminer build for bitburner and I got lots of errors like:
[2014-01-13 16:49:12] BTB 4 usb transfer read error(-1): LIBUSB_ERROR_IO
Performance is also signficantly worse, at about 325GH/s (about a 50GH/s drop).
I have another stack of 8 bitburner boards connected with 5 USB cables (the rest via CANBUS). It has always performed worse than the other at about 340 GH/s. It's been connected to a raspberry pi too.
The worst part is that a couple times a day, they wiill just crash with a USB error and I'll have to power cycle the boards and restart cgminer. This never happeend with the Linux PC. Only with the raspberry pis.
Has anyone had any success getting the bitburners to work reliably with raspberry pis or do I just need to invest in some more linux PCs?
I believe it's a problem with the raspberry pi design. I don't know if they ever fixed it on later models but it had a known USB issues. The official response was that it was a power supply issue. See: http://www.raspberrypi.org/phpBB3/viewtopic.php?t=12097
An alternative some are using is a TP-Link router with OpenWRT. See: http://wiki.openwrt.org/toh/tp-link/tl-mr3020
Also make sure you never use a USB1 hub. It may work for a while but it will cause random USB issues because of how slow it is.