Grant Edwards wrote: > I just bought a new 6TB WD Red Plus drive to replace a couple older > drives (one of which had generated an uncorrectable error email from > smartd). I decided that I'd stick it in an external USB-3 SATA drive > "dock" thingy from Thermaltake and do some testing before installing > it. > > Using smartctl, I ran a "short" self test and a "conveyance" test, and > both passed. > > Then I started a "long" (extended) self test. According to the drive, > that should take 640 minutes (a bit under 11 hours). It almost > immediately reported test running with 90% remaining. A couple > hours later, it still said 90% remaining. I stopped the test, ran > another short test. Messed around with some other smartctl commands, > and started another "long" test. Again, it immediately said 90% > remaining. After 20 hours, it still said 90% remaining. > > Tests getting stuck like that seems to be pretty common. > > Some time spent Googling found me two suggestions: > > * The test is stalled because the disk is busy. > > * The test is stalled because the disk is idle. > > Apparently, they're both valid. > > The self-test runs in the background when the drive is not busy, so if > the drive is heavily loaded, self tests can take a lot longer. But, > if the drive is _completely_ idle, it might spin-down and go to sleep > (which pauses the test). This is reportedly more likely to happen when > the drive is attached via a USB-SATA adapter [I don't know if that's > true]. > > Sure enough, if I waited 5-10 minutes and asked for the test status, I > would hear the drive spin-up when queried. > > So I ran a "watch" command to query the drive every 10 seconds: > > watch -n10 smartctl -d sat -c /dev/sdc > > That seems to keep the drive spinning without doing any actual R/W > ops, and within an hour the status changed to 80% remaining. About 6 > hours after that, it's now 20% remaining. > > So the moral to the story is: when running an extended self test on a > drive, you don't want it to be busy, but you also don't want it so > idle that it spins down goes to sleep. > > Maybe everybody else already knew that, but it took me an hour or two > to figure it out... > > >
That's some neat info. You could likely set 'watch' to a couple minutes and still be fine but as you say, it doesn't really do anything put poke the drive to keep it awake. lol I might add, this is why I like eSATA external drives. They don't sleep. They function just like a drive that is installed inside my system. If it goes to sleep, I told it to nap. Good of you to post this. This just could help someone one day that runs into this. Dale :-) :-)
