HP-UX Reference (11i v2 07/12) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

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scsi_disk(7) scsi_disk(7)

primarily intended for optical media, some systems may support write veriﬁcation on normal disk devices.

The SIOC_VERIFY ioctl veriﬁes that a media area contains valid data (that is, data that has been

correctly written). Veriﬁed media will not cause I/O errors when reading is attempted. The media area to

be veriﬁed is speciﬁed via the

start_lba and block_cnt ﬁelds. Although veriﬁcation is intended pri-

marily for optical media, some systems may support verify operations on normal disk devices.

The

SIOC_WRITE_WOE

ioctl controls the write mode used for magneto-optical disk devices. Normally

magneto-optical write operations require two physical head passes. The ﬁrst pass erases the media area to

be written. The second pass actually writes the data. Write-without-erase mode dramatically increases

write performance by skipping the ﬁrst (erase media area) pass. To ensure that the correct data results, it

is essential that write-without-erase operations be performed only on media that is known to be blank (pre-

viously erased or never used). The

SIOC_WRITE_WOE

ioctl can be used to enable or disable write-

without-erase. A zero value disables write-without-erase. The value

1 enables write-without-erase.

The

SIOC_ERASE ioctl allows media areas to be explicitly erased. The media area to be erased is speciﬁed

via the start_lba and block_cnt ﬁelds. Media areas erased in this manner can be written using

write-without-erase mode. Note that an erased media area is different from a media area written with

some data values (e.g. zeros). An erased media area should not be read. Attempting to read an erased

media area generally results in an I/O error.

The SIOC_VERIFY_BLANK

ioctl veriﬁes that a media area has been erased and is suitable for being writ-

ten using write-without-erase mode. The media area to be veriﬁed is speciﬁed via the

start_lba and

block_cnt ﬁelds.

The following optical disk device speciﬁc information is included from <sys/scsi.h> :

#define SIOC_WRITE_WOE _IOW(’S’, 17, int)

#define SIOC_VERIFY_WRITES _IOW(’S’, 18, int)

#define SIOC_ERASE _IOW(’S’, 19, struct scsi_erase)

#define SIOC_VERIFY_BLANK _IOW(’S’, 20, struct scsi_verify)

#define SIOC_VERIFY _IOW(’S’, 21, struct scsi_verify)

/* structure for SIOC_ERASE ioctl */

struct scsi_erase {

unsigned int start_lba;

unsigned short block_cnt;

};

/* structure for SIOC_VERIFY_BLANK and SIOC_VERIFY ioctls */

struct scsi_verify {

unsigned int start_lba;

unsigned short block_cnt;

};

FILES

/usr/include/sys/scsi.h