[comp.sys.ibm.pc] Hard Disks, Head Parking, and CRASHES

Ralf.Brown@B.GP.CS.CMU.EDU (07/21/88)

In article <3394@louie.udel.EDU>, cayz@udel.EDU (James Cayz) writes:
}2. Is it common for disk drives to seek to 0, recalibrate, and then seek to
}infinity on park&lock?  I would do it like this: "Power down: Seek to MaxCyl,
}NOW!", and forget the recalibrate. That can be done at powerup, when there is
}lots of (clean?) power!!!  Or is there something inherently wrong with this?

I would think that there wouldn't be any time to do anything but seek to the
parking area.  My Seagate 4051 goes "clunk" on powerdown as the heads are 
retracted.  The "clunk" is louder the nearer to cyl 0 the heads are, as the
spring that seems to be used to retract the heads has more time to accelerate 
them....  For this reason, I run a "park" type program to move the heads to 
the last cylinder before powerdown.  Never had any problems in that regard.

I also run a timed-park TSR, but I modified it first.   It was seeking to
MAXCYL+1, which makes the 4051 retract and lock the heads, requiring a 
recalibrate on the next disk access.  Now it just seeks to MAXCYL to keep the
heads away from the FATs and root dir....

}3.  Are there any utilities out there made to seek to a user-supplied cyl?
}Ideally, we would like to move the heads to around cyl 5 (past the FATs &
}Parition table) and them remove power...

Note that the heads are 50 to 100 cylinders wide, depending on the design of 
the heads and the number of cylinders in the drive, and whether the drive has 
3-inch or 5-inch platters.


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