A hard drive "slowing down and stopping", can be a hardware
issue with the drive. You can use the Western Digital disk
drive test software, to determine if the drive is still
healthy.
Another source of performance issues, is actually WinXP. I've
had problems here, where after about 1TB of writes, NTFS becomes
so slow I got a "Delayed Write failure". This seems to be a function
of memory management in WinXP, but I don't have a cure for it. I
had a failure like that, when I left something running overnight.
I've also had similar symptoms, while recording from a VCR with
a WinTV card (NTFS uses more and more CPU as time goes by).
*******
The following assumes nothing in the previous paragraphs apply.
The WD20EARS is a Caviar Green. Using the feedback tab here...
http://www.newegg.com/Product/Product.aspx?Item=22-136-514
"d4nguy 1/9/2012 6:06:29 AM
It took months to figure out that it was the fact that these "economical"
drives spin down when not in use to save power. This causes lag when a
file is accessed and slows everythign down."
The WD6400AACS is a Caviar Green as well.
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136298
Found this.
http://community.wdc.com/t5/Desktop-Portable-Drives/Attempting-to-disable-APM-failed/td-p/417006
I can find a copy of the utility here. The deceiving part, is
they make it look like the utility only works on certain drives.
http://support.wdc.com/product/download.asp?groupid=609&sid=113&lang=en
OK, got some different info at the top of this page.
http://www.readynas.com/forum/viewtopic.php?p=233472#p233472
"Sorry, but our agent didn't know that this policy was just changed.
Current WDIDLE3 works with the RE and GP drives listed below.
RE Drives - WD1000FYPS-01ZKB0, WD7500AYPS-01ZKB0, WD7501AYPS-01ZKB0
GP Drives - WD20EADS, WD20EARS, WD15EADS, WD15EARS, WD10EADS, WD10EARS,
WD8000AARS, WD7500AADS, WD7500AARS, WD6400AADS,
WD6400AARS, WD5000AADS, WD5000AARS
WDIDLE3
http://support.wdc.com/product/download.asp?groupid=609&sid=113&lang=en
refers to the WD Tool
RE2GP Idle Mode Update Utility
File Name: wdidle3_1_05.zip
File Size: 170 KB
Version: N/A
Publish Date: 4/2010"
Now, that's a DOS utility, and with a DOS utility, you have to
figure out whether it'll work in a Command Prompt window,
or will only work by actually booting MSDOS. (MSDOS equivalents
exist, such as FreeDOS, so that's not as outlandish as it sounds.)
I presume what that'll do, is change the spin-down policy. Whether
they're spinning down to protect the platters, is anyone's guess.
In the past, spindown was a cheesy way to control drive temperature,
such as when a Caviar Green is used in an external enclosure without
a cooling fan. But if for some reason the platters weren't rated
for continuous service, spindown might be another solution for
that. If they allow that utility to work on a Green drive,
I'm guessing they're willing to support any extra warranty claims
that might result.
*******
If you were having problems with the Hitachi, you could use the Hitachi
Feature Tool to try changing APM. But there's no point attacking
the Caviar drives that way, unless someone else has succeeded
by using that approach.
*******
And even with all of that, you'd first want to verify it
wasn't a Power control panel setting that was spinning
down the drive. In Windows 8, when I installed Release Preview,
I had to disable the spindown feature there, in the Power schema,
because it was actually damaging data contents (causing
unnecessary CHKDSK automatic runs). Preventing spindown
in Windows 8 RP, stopped that from happening. I haven't had a
CHKDSK autorun since then.
*******
As for the reference to "SCSI" drives, you know they're not
SCSI drives. In the old days, some drivers used the pseudo-SCSI
stack on Windows, to implement a storage driver. And then, you'd
see references in Device Manager to SCSI. Windows would send a
SCSI CDB (command/data block) to the third-party storage driver,
and the driver would convert it to an ATA command of some sort.
A second reference to SCSI, can come about from SAS equipment.
As in Serial Attached SCSI. SAS uses the same cabling as SATA,
but the protocol has differences. In the article here, it
suggests a SAS hardware controller, can work with SATA drives.
But such a thing on desktop systems isn't too common, so I'll
assume the reference is instead coming from the way the driver
is designed (pseudo-SCSI). Perhaps even, a side effect of selecting
AHCI mode ?
http://en.wikipedia.org/wiki/Serial_attached_SCSI
"SAS controllers may connect to SATA devices, either directly
connected using native SATA protocol or through SAS expanders
using SATA Tunneled Protocol (STP)."
In any case, your drives aren't the "old fashioned, fat cable SCSI".
Paul