Dead RF31 DSSI Disk.. final Question..

Paul Koning paulkoning at
Tue May 12 12:39:39 CDT 2015

> On May 12, 2015, at 1:28 PM, Holm Tiffe <holm at> wrote:
>>> ...
>> The exerciser showed some correctable soft errors, wich is pretty much
>> normal I think. Reformating the drive should simply "freshen up" the data
>> tracks but erase should do the same in this regard.
>> Since the distks aren't containing anything interresting, it would be the
>> right time now to do a reformat.
>> I think the head assembly has an voice coil engine anyways, so servo tracks
>> are needed to do the positioning. It is clear that they aren't affected from
>> a reformat...
> Johnny the success proves that I'm right. After "erasing" the disk the
> exerciser run found no soft read errors anymore. "Soft error read count 0".
> BTW: This was the disk that I've hammered :-)

Servo data is unaffected by formatting.  If you have read errors, simply overwriting the drive may be sufficient, but certainly formatting would.  That assumes such an operation even exists; in some cases, when people say “format” they simply mean pattern-checking the drive and/or creating a new empty file system on it.  For example, in PDP-11 disks, a “real” format operation that does more than just rewrite the data appears only on a few drive models: RP03 and RK05 do, most others don’t.  Some MSCP drives also, I think, but those only via magic code running on the controller, not from the OS.

On drives with dedicated servo tracks (RP04 family for example) the servo head is only a read head.  But in all cases, servo writing is done on specialized machines, and only at the factory.


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