This has been asked before, and on other sites, but I'm not sure there has ever been a definitive answer.
I'm running Samba under Raspbian on RPi model B (original version -- not the recent upgrade). FWIW, /proc/version gives Linux version 3.10.25+ (dc4@dc4-arm-01) (gcc version 4.7.2 20120731 (prerelease) (crosstool-NG linaro-1.13.1+bzr2458 - Linaro GCC 2012.08) ) #622 PREEMPT Fri Jan 3 18:41:00 GMT 2014.
For many months, the thing was fine, but then Samba began to crash regularly, and dmesg indicated input / output errors. Rebooting the RPi fixes it, but only for a while (at most a few days. often less).
I'm using an external USB HDD with its own PSU, so I'm not powering it off the RPi. Some sites have suggested the issue would normally lie with the disk, but that seems to be fine if attached to other machines. There's also been a suggestion that the problem may be the SD card, but I believe it is on the approved list, and in addition I have tried both rewriting it and replacing it. In case it's relevant, I make use of Samba only rarely -- often for no more than a few minutes a day.