I am just getting up with the Western Digital 1.5 TB WD15EADS drives, upgrading from Seagate 1TBs. I did a lot of research for issues involving these drives. There is quite a bit of info available, but I did not recognize a definitive pattern with a proven resolution. My own experience - being a new install - does not add any new clarity as my time with the configuration is limited. I've made configuration changes to the drives on a pro-active basis and not in response to any negative events.
Two main issues appear to be in play with these drives in a READYNAS RAID device
1) RAID stability due to disk-based error-correction features and
2) High Load Cycle Counts (LLCs).
I believe issue 1) to be serious and 2) as not so serious.
Two legacy WD utilities can be used to adjust the drive configurations to address these areas. My conclusion to use these WD utilities - WDTLER and WDIDLE3
, respectively - was simply that "it couldn't hurt." They can be found in the nooks and crannies of the web.
WDTLER usage is meant to avoid conflict between the on-disk error handling and the RAID controller's understanding of the disk response/integrity. Not having WDTLER-enabled has been linked with the possibility of having a drive drop out of the array due to "unresponsiveness" when the disk was undertaking it's own error correction. This seems to be a very real issue. Your own experience might bolster this case. These drives have NOT been explicitly engineered (or perhaps marketed) to be used in a RAID configuration. As such their default operating configuration is "stand-alone - desktop" as opposed to "enterprise" drives (which command a premium price.) But that does not necessarily mean they should be precluded in a RAID configuration. The WDTLER utility will allow tweaking the drive for better participation in a RAID situation. See http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery
for more background.
The IntelliPark feature of the drives has been linked with high Load Cycle Counts being reported in the drives SMART data. Whether the high counts are meaningful and degrade the life of the drive is not clear. Using the WDIDLE3
, the idle park time can be adjusted to be longer or be defeated altogether. Defeating it would, presumably, undercut the IntelliPark feature. As a result, the drive might not be as "green", however. Personally, that is not my main criteria when selecting a disk. I bought on capacity and price (the "I" in RAID) primarily. Here is a link with much back-and-forth on the high LLC count issue: http://www.silentpcreview.com/forums/viewtopic.php?p=457909&sid=151f78a17e4944374adc112c558a98b1
. Keep in mind that the EXACT sub-model of your WD15EADS may impact high LLC reporting.
Both utilities are DOS-based. To run them you will need a bootable floppy or CD. Creating a bootable CD can be more involved than building a bootable floppy and require specific CD burning s/w. I suggest the floppy if you have a PC with a floppy drive and can round up a floppy disk.
I'm going to make some assumptions about what is available to you and others in order to make the adjustments to the drives
1) PC with Windows
2) PC with SATA support and a floppy drive configured to boot from the floppy when present (configured in the BIOS)
3) WDTLER.EXE and WDIDLE3
Building the floppy:
1) Scrounge a floppy
2) Get into Windows
3) Place floppy in floppy drive
4) Go to "My Computer"
5) Right-click on Floppy drive (probably Drive A or B)
6) Select "Format..." from the short-cut menu
7) On the Format dialog, check the option for "Bootable MS-DOS Start-Up Disk" (or similar)
8 ) Once format is complete, copy your WD utility files to the diskette
Preping the Hardware:
1) Connect your WD15EADS disks to the SATA controller and power supply of your PC
If you can connect both at the same time, then great. If not, you'll repeat this process for each drive
2) Disconnect any WD drives already installed in the PC. Any WD disks in the PC will be affected by running the utilities - so if you don't want them tweaked unplug them.
Running the Utilities:
NOTE: Running these utilities should not be destructive to disk content. But be wise and make sure you have backups in case things so sideways.
1) Put boot floppy with utilities in your floppy drive of the PC. Assume this is A: drive.
2) PC will boot to DOS and drop at the prompt of the floppy "A:>"
3) Type "TLERSCAN.BAT" to get the current TLER values for the drive(s)
4) Run "WDTLER -r7 -w7" to enable Time Limited Error Recovery of 7 seconds for Read and Write for all WD drives. Alternately, you could run "TLER-ON.BAT"
5) You'll see adjustments made reported for drive(s)
6) Run "TLERSCAN.BAT" again to confirm settings. Mine kept the 7 seconds on Reads and had 0 seconds for Writes. No worries, this is the recommendation anyway.
7) Run "WDIDLE3
/R" to view current IDLE configuration
8 ) Run "WDIDLE3
/D" to disable IDLE time parking
9) Run "WDIDLE3
/R" to review adjustments made. Should see IDLE "disabled" now.
10) If you have to do multiple drives, restart PC and repeat steps for each drive
That's pretty much the whole story. I will update with any specific performance issues I have with these drives in this configuration. I will also report success in the Community HCL if things go well for a while.
Edited to fix command for WDTLER inquiry command. Previously misspecified as "WDTLER /R"