I have two external HDD enclosures containing one LVM. One of them sleeps and wakes properly. The other, which holds 2 HDDs will sleep properly, but refuses to wake up unless the Pi gets a hard reboot.
I have gone through and e2fsck'd the whole LVM. Furthermore, I have scanned for bad blocks and have done the typical "is my hard drive bad" troubleshooting. The LVM works just fine on a desktop Arch Linux install.
Both are self-powered drives, and no USB hub is involved. I know that I could, in theory, use hdparm to set a ridiculously long time before sleep, but I'd really rather my drives be able to sleep in order to improve their longevity.
Any ideas as to why the drives won't wake up? Or at least a starting point?