Differences between WRPROTECT and VRPROTECT

George Penokie gop at us.ibm.com
Mon Nov 20 15:21:37 PST 2006

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There is no data written to the media with a VERIFY command. There is data 
sent to the device that is only to be compared with what is already on the 
media if the BYTCHK bit set to one. In that case the protection 
information moved with the data from the initiator to the target is used 
to check the data that is sent based on the requirements listed in table 
64. The corresponding data is read of the disk and is checked using 
protection information read from the media with the data as defined in 
table 63. Then the data from the initiator and the data read from the 
media is byte checked and the protection information is byte checked as 
defined in table 65.
Bye for now,
George Penokie
Dept 9A8 030-3 A410
E-Mail:    gop at us.ibm.com
Internal:  553-5208
External: 507-253-5208
Gary.Franco at Emulex.Com 
Sent by: owner-t10 at t10.org
11/20/2006 02:11 PM
<t10 at t10.org>
Differences between WRPROTECT and VRPROTECT
Is it the specification or my lack of understanding ? here is the issue:
Isn?t a VERIFY for all intents and purposes the same as a WRITE command as 
the DATA is sent to the device for verification.
In a WRITE command if the WRPROTECT bits are 000 (no protection data 
available) the target device create its own protection information and 
writes it to the disk.
This same operation is not called out for the VERIFY, therefore wouldn?t 
all the checks fail by default?
Gary Franco Consultant Engineer
Emulex Network Systems
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