How to know valid APM levels for WD7500BPKX?

WD Internal Drives Desktop & Mobile Drives
1

Hello there,

I have this model rotating drive installed in my MacBook Pro, and since the Load_Cycle_Count parameter is too high to my taste, I would like to know what are the valid APM levels for this drive in order to manually set it at a level that wouldn’t put so much pressure on it. I can’t find it in the specs sheet.

All Google links show the actual level depends upon each manufacturer’s firmware. Any idea where I could find this info?

2

Based on my observation so far, non WD*X disks use APM Level 128 while WD*X disks use APM Level 96. If you do a search on the Internet, you’ll find that any APM level below 128 will allow the hard disk to spin down/park. Levels 128 and above will not allow the hard disk to spin down/park. So you’ll have to check the APM level of your hard disk.

I’ve not really tested the impact of idle3 on these disks. If your hard disk’s APM is already at Level 128, it’s probably idle3 that triggers the autopark. If your hard disk’s APM is at Level 96, then you’ll probably have to fine tune both the idle3 timer and APM timer. There’s no easy way - you’ll have to start from a reasonable value, observe, and adjust accordingly. I’d say 5 minutes is reasonable.

3

That’s the point, I can’t see the APM level in a Mac, there’s no utility currently able to report it.

I already know 128 is usually the power saving  setting, on many drives, WD excepted apparently, and 255 completely disables it. What’s more difficult is that settings are not necessarily incremental like 128, 129, etc. and depend on manufacturers. That was my question, what are the valid levels for WD?

4

The oldest 2.5" drive I had which is an 80GB is Level 128. Recent WD*PVX is Level 96. So far I’ve only observed these 2 values. Let’s see if there are others who are able to answer you.

5

Well I just booted a Live DVD of Linux, and hdparm -B reported value 254 while plugged in, and 127 when the machine was unplugged. To what extent these values are the ones intended by WD I don’t know. I tried to set it to an arbitrary 130: the drive would accept it and it held as long as the computer wasn’t unplugged (or plugged in). But as soon as I pulled the cord, it reverted back to 127. I am beginning to wonder if the Mac only allows for two values that would be stored in NVRAM (?).

The idle3 parameter was factory set at 8 seconds, which is much, much too short IMHO, as it averaged more than 70 load-unload cycles per hour. Unfortunately I wasn’t able to change it. I freaked out when hdparm claimed that it wanted an additional --please-destroy-my-drive flag when a numerical value was passed along -J flag, since its reverse-engineering of the proprietary idle3 function wasn’t perfect.

I wasn’t able to run the original DOS version of wdidle3.exe from Hiren’s Boot CD as it simply refused to launch (probably giving out an error I couldn’t read since it flashed very briefly).

And, to what extent do the APM values interact with idle3?

6

As far as I know, idle3 defaults at 8 seconds, and APM at 20 seconds. I’ve had a very limited number of hard disks to test with. If the autopark persists with idle3 disabled (or in a way, quicker than the value you configured) then it’s time to look into APM. idle3 only kicks in when your hard disk is idle for 8 seconds, not every 8 seconds. Same goes for APM.

There is a Unix program available for idle3 ( http://idle3-tools.sourceforge.net/)) and APM ( http://apmtimer.sourceforge.net/)..) APM timer is tested on some out of warranty drives to avoid voiding my warranty, so you can guess their age. So you should take note that changing the idle3 timer and APM timer could void your warranty too.

7

idle3-tools appears decent, but as you point, it would void warranty (TBC by WD), as the other tools. 8 seconds of idle time before it kicks in, I maintain that’s too short. I have got two other drives from this series fail within 18 month. Perhaps WD considers better to issue an early replacement due to faulty factory setttings than attempt to make them last longer by easing the pressure on the heads? (at least it’s not bad sectors!)

8

If you think 8 seconds is short, I’ve came across a disk with 4 seconds of idle3.

Even if you use wdidle3.exe, you might still void your warranty. I think there is a list of disks that is “compatible” with wdidle3.exe. As long as your model is not listed there, you’re doing at your own risk and I believe WD reserves the rights to provide a warranty claim should it die.

9

So they might replace it if failure occurs due to excessive number of cycles, but not if I tried to correct the issue using unsupported tools.

10

This may be a bit late, but Ubuntu Linux uses udev in combination with something called laptop-mode tools in an attempt to create better power usage when a machine is unplugged.  So udev listens for when the power is connected and disconnected, and upon response of that state being changed, runs the laptop-mode scripts to, in turn, change the APM level of disks to enable and disable spin-down whether connected to a power source or not, respectively.

So the disk only knows one APM level at a time.