In August, 2010 I purchased a ReadyNAS pro business edition and wanted to get the most storage for the dollar.  WD20EADS drives from Western Digital looked like a great option because despite being consumer drives, two critical RAID requirements could simple be enabled on these drives.

The first is feature is to disable a head parking feature with a utility called wdidle3.  If left alone, this feature which normally saves power on a desktop, will lead to an excessively high Load Cycle Count in a RAID environment causing potential failure in the long term.  Good information about this abounds on the internet so I won’t cover it specifically, here is one opinion (link) .  With aggressive head parking disabled, my LLC count is below 300 for all of my almost 3 year old drives which are on 24×7 which is excellent.

The second is to enable TLER.  At the time of my build I believed TLER to be critical and currently no longer believe it to be critical in this RAID environment.  Here is a short breakdown. In brief, it provides for error recovery for a hard drive that does not respond right away in a RAID array to prevent the array from dropping the drive.

Moving on to the functional, I turned on TLER (7 second read and write function) and disabled the aggressive head parking.  I did it with the tools below.

fdoem-iso (click to download iso, 32bit only)

This is an iso with wdidle3 preloaded and TLER capability preloaded.  Just write this iso to a CD or use tools (not described here) to boot a USB stick with this iso.  Once you boot, type “wdidle3 /d” or in some cases (if this first command does not work) “wdidle3 /s0” to disable aggressive head parking.  Some drives will not allow these options and you can alternatively run “wdidle3 /s300” which will only park the head once every 300 seconds which will at least greatly alleviate the issue.  “wdidle3 /r” will report the status.  To turn on TLER, just type tler-on which enables TLER with a default 7 second read and write.  You may run tler-scan to see the status of TLER on your drives.  wdspinup is also on this iso which I did not use but gives the user spinup time control.  WDTLER.exe and wdidle3.exe as well as hdaccess.exe are also included.

fdoem-cdmaker (click to download tool, 32bit only)

This is the tool I used to create the iso.  You can add other functions or tools to the CDROOT directory to customize your own iso.  Just add what you want to the CDROOT directory then run makeiso.bat

fdoem-64bit (click to download tool, I have not tested 64bit)

I also found this tool here. I understand this is the same tool that will now operate on 64bit systems.

Now, onto the main reason for my post.  I recently had two WD20EADS drive failures concurrently which stemmed from one bad drive and a failing ReadyNAS.  I will cover the failure and resolution in another post but I lost all my data on my ReadyNAS (~8TB worth).  Fortunately, I have a backup plan which teams Dropbox and Crashplan on the ReadyNAS as well as client machines which led to very limited actual data loss.

For anyone with these drives, my recommended procedure going forward is to take the ReadyNAS offline at least once a month and perform an offline disk test (click here to see how) .  The reset button is on the back of the machine in a small hole above the rj45 connections.  I recommend every 6 months, shutting down the ReadyNAS and taking the drives out for a full, extensive scan with a tool like WD Diagnostics or similar free tools to validate full function as the ReadyNAS offline tests are not low-level scans.

The WD20EADS drives were still under warranty though not by much.  I was able to get replacements which are WD20EARX drives.  I did have to run the wdidle3 tool on the near EARX drives but TLER cannot be enabled.  Apparently WD caught on to what users where doing and functionally disabled the possiblity of TLER being enabled on the green drives.  So far the EARX drives are working and run about 5-8 degrees Fahrenheit cooler than the EADS drives.  I hope the lack of TLER will not prove problematic.

In the end, the cheap WD drives cost me more money and time and effort than they saved.  On initial purchase, one of them was DOA.  I believe no cost reasonable enterprise drives were available at the at 2TB time but going forward I will be using only drives on the ReadyNAS Hardware compatibility list .  At the moment I will use the existing drives but with the new testing procedure in place described above.  Going forward, I only plan to use enterprise drives such as the RE4 WD series or Constellation Seagate series.  Were I to choose today, I would get 3TB Seagate Constellation ES2 drives ST33000650NS .

UPDATE (2/17/2013):
I ended up purchasing 6 ST33000650NS after the replacement WD20EARX drives showed ongoing ATA failures and the old WD20EADS drives had additional failures.