[mythtv-users] warning for anyone with western digital green drives

[Ronald Frazier]

On Thu, Jan 5, 2012 at 2:57 PM, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> The design is validated to a million cycles, and WD expects them to
> handle significantly more than that without issue.  The SMART tools
> report an incorrect maximum for the drives (they say 300K, but I don't
> know whether that's because WD put the wrong value in or because the
> tools are interpreting it wrong--i.e. as with Seagate, perhaps WD is
> using a "proprietary" encoding for some values).

What do you base that on? I'm looking at the spec sheet from western
digital, and it explicitly says 300,000:

http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701229.pdf


> Note, also, the best fix for the issue is to fix your system to not
> abuse the file system--i.e. configure your system to use it
> appropriately.  After all, if you actually let the drive idle, rather
> than waking it every 10-30s, it will spend a majority of its time at
> idle 3 power usage (0.7W) versus 3.3W at idle and 5.3W for read/write.
> (Numbers based of WD20EARS -
> http://www.wdc.com/en/products/products.aspx?id=120 ).


Uh, how exactly do you "configure your system appropriately"? Linux
systems are designed to do a lot of logging. Cron jobs can be
triggered every minute. Lots of backend processes run continuously and
log to file.



> Note, also, that the wdidle3 tool is
> not validated to run on any drives other than those listed at
> http://support.wdc.com/product/download.asp?groupid=609&sid=113:
> -----
> This firmware modifies the behavior of the drive to wait longer before
> positioning the heads in their park position and turning off unnecessary
> electronics. This utility is designed to upgrade the firmware of the
> following hard drives: WD1000FYPS-01ZKB0, WD7500AYPS-01ZKB0,
> WD7501AYPS-01ZKB0.
>
> CAUTION: Do not attempt to run this software on any hard drives other
> than what is listed above. Please make sure that the computer system is
> not turned off during the firmware upgrade. Doing so may damage the hard
> drive beyond repair and your data may be lost.
> -----

True, but plenty of people have used it on other drives without any
problems. It worked fine on both my 2TB and 3TB green drives. But
yes...use at your own risk, obviously.


> Again, see
> http://wdc.custhelp.com/app/answers/detail/a_id/5357 for some
> suggestions, but there are a lot more out there when you search on "low
> power linux" or "laptop mode linux" or similar.  Oh, and note, also,
> that having only MythTV recordings on the drive may "solve" the issue
> for you, too (assuming MythTV recording file writes are <8s apart, and,
> IME, they seem to be).

And there you will note that #3 under ways to properly configure it is
to use the wdidle3 utility. So even WD considers that a proper way to
configure your system.


As far as the power savings, 2 watts is nothing. That's $2 a year.
I'll pay that vs risking the drive. I should also note that I did some
testing with the drive, and I really didn't see any power savings from
this. I can't explain why, but I hooked up my kilawatt and monitored
the drive. 8 seconds after my last access, I would see it briefly drop
by 2 watts, but then it would immediately jump back to normal. At
first I thought something else was reactivating the drive, but I could
let it sit there indefinitely and the power level would never again
jump up or down. If I then accessed the drive (so that I knew for
certain it was active) the power consumption would not change, but
then 8 seconds later it would briefly drop by 2 watts, and then a few
seconds later return to the normal level and stay there indefinitely.
I really can't make sense of it, but that's what it was doing

-- 
Ron Frazier