Media Test - HP C2488A Technical Reference Manual

Media Test
RND (Random). This bit selects either random or sequential addressing. The media testing
begins with the logical block address specified in the CDB. If RND is set to zero (0), the test
proceeds sequentially from the specified logical block. Logical block zero follows the last
logical block on the media when using sequential addressing. If RND is set to one (1), the
next address is generated randomly from any block on the media.
RST (Reset Seed). This bit is used only when RND is set to
ope
(1). When RST is set to
one (1), the Target initializes its random number seed using the specified block address. This
capability provides a method to enable a repeatable sequence of random addresses for pairs of
MEDIA TEST commands (i.e., a write followed by a read). If RND is set to one (1) and RST
is set to zero
(0),
the random number seed is not reset. If RND is set to zero
(0),
RST must
also be set to zero (0).
Address. This field specifies the media test area; refer to the previous explanation for the
PHYS bit.
Transfer Length. This field indicates the number of blocks to be tested, unless terminated
by an error. An unrecoverable error terminates the MEDIA TEST command and generates
CHECK CONDITION status with the appropriate sense information. If only recoverable
errors occur, the media test will run to completion and return a CHECK CONDITION status
with sense information set for the last recoverable error which occurred. Information on any
additional errors can be obtained from the drive error log. A transfer length of zero shall not
cause any media transfer to occur and shall not be considered an error.
On a sequential media test, if the Transfer Length is greater than the length remaining from
the start address to the maximum block address, the test will continue to run from address
zero (0) after the maximum block address is reached. This is not considered an error. This
"wrap around" may occur more than once during a long test.
For random tests, only single block operations are performed. The transfer length field
indicates the number of these operations to be performed.
DRAFT Vendor Unique Command Descriptions B·17
1/18/93 09:58