On 7/28/2005 6:52 AM, [EMAIL PROTECTED] wrote:
In a message dated 7/27/2005 9:19:58 P.M. Central Daylight Time,
[EMAIL PROTECTED] writes:
I was wondering if ZAP would/not allow one to
retrieve data from a track that had been "cleared" by writing R0 or EOF at
beginning of the track. I guess Radoslaw Skorupka's English comes out better
than mine. Can I blame it on American television? Hmm, no, come to think of
it. English is NOT spoken on 'American' television'.
?Anykahow, will ZAP recover data as asked?
z/OS performs data erasure by telling the control unit to erase tracks.
That results in the track having only an R0 record, and the rest of
the track is overwritten with binary zeros. No program that uses normal
CCW interfaces to the DASD can then read anything on the track.
Writing an EOF is different. That replaces just one block on the track,
leaving the rest of the data (in the subsequent blocks) intact. ZAP and
other programs can read the rest of the data in that case, but cannot
read the original block that you overwrote.
Walt Farrell
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