User guide

ManualsBrandsCorvus systems ManualsComputer equipmentTRS-80 II

Sparing Tracks

The REV B Corvus drives contain a total

of

seven extra tracks for

the user area. These tracks can be used in place

of

tracks in the

user area

if

a user track is found

to

be defective.

Defective tracks are 'spared out' by

making

the disk controller

simply skip over them (rather than re-direct requests to a separate

spare

track

pool). This choice

of

sparing methods was chosen to

allow

our

mirror backup system to

function

more simply. One

undesirable consequence

of

this choice

of

methods is that all the

data on the disk beyond the newly 'spared track'

will now

be

offset

one

track

from its previous position.

Thus

this data must

be

backed

up

on some external storage

unit

before the

track

is

spared. The data can then

be

restored

after

the new spare

track

table is made.

Corvus provides a diagnostic program

to

users which makes the

process very simple.

BACKUP YOUR DRIVE BEFORE SPARING TRACKS

OUT. FAILURE TO

DO

SO WILL RESULT

IN

THE LOSS

OF

ALL

DATA

BEYOND THE SPARED TRACK.

YOU

WILL

HAVE

TO RESTORE FROM A MIRROR BACKUP

OR RE-INITIALIZE YOUR SYSTEM.

There are several possible ways

of

discovering bad tracks.

You

may

getI/O

errors during normal operation. The bad spots may

show up in a

CRC/FORMAT check.

If the drive returns I/O errors in

the

same

spot

consistently, you

probably have a bad track. Calculating

the

physical location

of

the

bad

track

from

the

information

available

to

you is

nearly

impossible. The best thing to

do

is run

the

diagnostic program and

select the CRC/FORMATcheck from the menu.

In

almost all cases,

the

error will show up in this diagnostic routine.

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