Hard drive unloading on shutdown

[Franklinstein]

Does anybody know any software for Classic Mac OS (System 7.5-9.1, HFS+ format) that will unload the hard drive heads on shutdown? A good number of Macs (PowerBook 5300, 2300, 1400, 3400, TAM) don't automatically unload the heads on shutdown, mostly because ramp-loading hard drives weren't a concern in the mid-90s. For drives up through to the late '90s, this wasn't a problem because hard drives would park automatically when power was removed, and they were all designed to do so unmanaged without damage. For newer drives, especially laptop drives, they will not automatically park at power-off; they rely on the host system to tell the drive to park the heads, then wait until the drive responds affirmatively before the system powers off. If the system does not include this routine, instead the drives do an emergency retract that flings the heads off the media and onto the loading ramp with excessive force. Emergency retracts significantly shorten the life expectancy of a ramp-loading hard drive (for example, a drive may be rated for 250k normal load cycles but only 50k emergency unloads). 

Old versions of LaCie Silver Lining (v5.31) had an option to park the hard drive's heads automatically when the system went for shutdown, which was especially useful for old stepper motor-based drives such as the 20MB MiniScribe unit in the Mac SE that would leave the heads in random spots if not told to park. This version of Silver Lining supports neither IDE or HFS+ so it's not really a choice. Newer versions of Silver Lining do not have an option for parking the hard drive, so I'm looking for an alternative for newer computers.

 

[Bolle]

such as the 20MB MiniScribe unit in the Mac SE that would leave the heads in random spots if not told to park.

My SE with System 6 does park the heads on its MiniScribe and even spins down the drive before it displays the "You may now shut down your Mac" message.

So System 6 must be sending the shutdown command to the drive. Pretty sure later systems should do that too. Maybe it was a SCSI only thing and it doesn't do it for IDE drives?

 

[BadGoldEagle]

The Matsushita in my SE/30 (running 7.5.1) parks its heads before shutdown but it doesn't power down. Perhaps that's specific to stepper motor drives?

 

[Franklinstein]

In my SE, the drive would park its heads by itself but only if it was left to sit for about 15 seconds; with the Silver Lining driver installed, it was instant.

All of the old voice-coil armature CSS drives were designed for the heads to rest on the media in a dedicated landing zone which had a fairly large margin, so it wasn't required for the drive to control the parking process. These drives would either let the heads drift into the landing zone on their own or utilize the still-spinning spindle motor to generate enough current to drive the heads into the landing zone. It was designed to be done in an unmanaged fashion and the drives had bumpers to keep the armature from being damaged.  

Ramp-loading drives need to have a controlled load/unload sequence to prevent damage to the heads, media, or loading ramps. Normal load cycles involve the drive's controller managing the torque and velocity of the voice coil to properly load and unload the heads. In an emergency unload, residual energy from the still-spinning spindle flows through the armature's voice coil, which causes the armature to move with excessive force and the heads to slam into the loading ramp, which can damage the heads or ramp and introduce contamination into the HDA. To avoid this, the OS has to tell the drive to park the heads before shutdown.  This procedure wasn't introduced in a portable Mac until the WallStreet/PDQ, and even then it only works under Classic Mac OS, not OS X. New World Macs all will do a proper park command to the hard drive before shutdown.

I'm trying to get something for my TAM because I'm running a modern ramp-loading drive and it's really rough on it.

 

[Franklinstein]

Some simple kind of shutdown delay, maybe 5-10 seconds (adjustable would be awesome), would be acceptable as well. Just something to give the hard drive enough time to flush its cache and hopefully unload the heads.

 

[Dog Cow]

Does anybody know any software for Classic Mac OS (System 7.5-9.1, HFS+ format) that will unload the hard drive heads on shutdown?

Try SCSI Parker

 

[Franklinstein]

Try SCSI Parker

Neat. That could be useful for some of the really old Macs in my collection. Now I just need a version that works with ATA disks in later PPC Macs.