When I bought the Plug I had a 1TB Western Digital hard drive ready for it, and all went well for about two months or so, until things started to go crazy with the mount and I eventually plugged it into my main Ubuntu 9.04 system which immediately reported a ton of SMART errors, lots of bad sectors (I'm not blaming the SheevaPlug, hoping it was just a bad coincidence). I replaced it with another Western Digital drive (they have a nice advanced RMA... just wish I never had to use it), and after six days, I started getting "Input/output error" and "device is busy". I restarted the Plug and all was fine.
Now, after exactly three days of uptime (I was streaming some media from the HDD/Plug and it suddenly died and I immediately ran uptime: 3 days, 1 minute), I got the error again. I wasn't able to umount normally (device busy), so I unplugged it and plugged it into my desktop, thankfully no SMART errors, all is well. I plugged it back into the plug and umount -l, mount -a worked.
Anyone else experience anything fishy like this? Willing to provide any other info if it helps.