[CentOS] Native ZFS on Linux - green drive cmt

Fri May 29 15:19:43 UTC 2015
m.roth at 5-cent.us <m.roth at 5-cent.us>

Chuck Munro wrote:
> As an aside, I have used only WD Black and WD RedPro drives for RAID,
> and not had any issues.  Green drives are scary :-)

It's the TLER that kills you. We tried some early 3TB greens in some of
our Penguins (OEM, rebranded Supermicro), and within a month, they'd start
giving DRDY errors. It turns out that there were two issues:
   1. They keep trying to spin down; ok in desktops, bad, bad, bad on
         And this is *not* RAID, just as a plain vanilla drive.
   2. Around '09, led by WD, they changed the firmware. Previously, you could
         use hdparm to set the TLER; after then, it was not user settable.
         TLER: if the drive finds a bad sector, this is how long it will
         before giving up, and rewriting it to another sector, marking
that bad.
         The greens try for up to two ->minutes<-; servers' firmware
expects this
         to happen in < 7 ->seconds<-. System is *not* happy....