NAME

SYNOPSIS

DESCRIPTION

Once a SCSI SANITIZE command has successfully started, then user data from that disk is no longer available. Even if the disk is power cycled, the sanitize operation will continue after power is re-instated until it is complete.

This utility requires either the --block, --crypto, --fail or --overwrite option. With the --block, --crypto or --overwrite option the user is given 15 seconds to reconsider whether they wish to erase all the data on a disk, unless the --quick option is given in which case the sanitize operation starts immediately. The disk's INQUIRY response strings are printed out just in case the wrong DEVICE has been given.

If the --early option is given then this utility will exit soon after starting the SANITIZE command with the IMMED bit set. The user can monitor the progress of the sanitize operation with the "sg_requests --num=9999 --progress" which sends a REQUEST SENSE command every 30 seconds. Otherwise if the --wait option is given then this utility will wait until the SANITIZE command completes (or fails) and that can be many hours.

If neither the --early nor --wait option is given then the SANITIZE command is started with the IMMED bit set. After that this utility sends a REQUEST SENSE command every 60 seconds until there are no more progress indications.

OPTIONS

-A, --ause

sets the AUSE bit in the cdb. AUSE is an acronym for "allow unrestricted sanitize exit". The default action is to leave the AUSE bit cleared.

-B, --block

perform a "block erase" sanitize operation.

-c, --count=OC

where OC is the "overwrite count" associated with the "overwrite" sanitize operation. OC can be a value between 1 and 31 and 1 is the default.

-C, --crypto

perform a "cryptographic erase" sanitize operation.

-d, --desc

sets the DESC field in the REQUEST SENSE command used for polling. By default this field is set to zero. A REQUEST SENSE polling loop is used after the SANITIZE command is issued (assuming that neither the --early nor the --wait option have been given) to check on the progress of this command as it can take some time.

-D, --dry-run

this option will parse the command line, do all the preparation but bypass the actual SANITIZE command.

-e, --early

the default action of this utility is to poll the disk every 60 seconds to fetch the progress indication until the sanitize is finished. When this option is given this utility will exit "early" as soon as the SANITIZE command with the IMMED bit set to 1 has been acknowledged. This option and --wait cannot both be given.

-F, --fail

perform an "exit failure mode" sanitize operation. Typically requires the preceding SANITIZE command to have set the AUSE bit.

-h, --help

print out the usage information then exit.

-i, --ipl=LEN

set the initialization pattern length to LEN bytes. By default it is set to the length of the pattern file (PF) or 4 if the --zero option is given. Only active when the --overwrite option is also given. It is the number of bytes from the PF file that will be used as the initialization pattern (if the --zero option is not given). The minimum size is 1 byte and the maximum is the logical block size of the DEVICE (and not to exceed 65535). If LEN exceeds the PF file size then the initialization pattern is padded with zeros.

-I, --invert

set the INVERT bit in the overwrite service action parameter list. This only affects the "overwrite" sanitize operation. The default is a clear INVERT bit. When the INVERT bit is set then the initialization pattern is inverted between consecutive overwrite passes.

-O, --overwrite

perform an "overwrite" sanitize operation. When this option is given then the --pattern=PF or the --zero option is required.

-p, --pattern=PF

where PF is the filename of a file containing the initialization pattern required by an "overwrite" sanitize operation. The length of this file will be used as the length of the initialization pattern unless the --ipl=LEN option is given. The length of the initialization pattern must be from 1 to the logical block size of the DEVICE.

-Q, --quick

the default action (i.e. when the option is not given) is to give the user 15 seconds to reconsider doing a sanitize operation on the DEVICE. When this option is given that step (i.e. the 15 second warning period) is skipped.

-T, --test=TE

set the TEST field in the overwrite service action parameter list. This only affects the "overwrite" sanitize operation. The default is to place 0 in that field.

-t, --timeout=SECS

where SECS is the number of seconds used for the timeout on the SANITIZE command.

-v, --verbose

increase the level of verbosity, (i.e. debug output).

-V, --version

print the version string and then exit.

-w, --wait

the default action (i.e. without this option and the --early option) is to start the SANITIZE command with the IMMED bit set then poll for the progress indication with the REQUEST SENSE command until the sanitize operation is complete (or fails). When this option is given (and the --early option is not given) then the SANITIZE command is started with the IMMED bit clear. For a large disk this might take hours. [A cryptographic erase operation could potentially be very quick.]

-z, --zero

with an "overwrite" sanitize operation this option causes the initialization pattern to be zero (4 zeros are used as the initialization pattern). Cannot be used with the --pattern=PF option. If this option is given twice (e.g. '-zz') then 0xff is used as the initialization byte.

-Z, --znr

sets ZNR bit (zoned no reset) in cdb. Introduced in the SBC-4 revision 7 draft.

NOTES

When a SAT layer is used to a (S)ATA disk then for OVERWRITE the initialization pattern must be 4 bytes long. So this means either the --zero option may be given, or a pattern file (with the --pattern=PF option) that is 4 bytes long or set to that length with the --ipl=LEN option.

The SCSI SANITIZE command is related to the SCSI FORMAT UNIT command. It is likely that a block erase sanitize operation would take a similar amount of time as a format on the same disk (e.g. 9 hours for a 2 Terabyte disk). The primary goal of a format is the configuration of the disk at the end of a format (e.g. different logical block size or protection information added). Removal of user data is only a side effect of a format. With the SCSI SANITIZE command, removal of user data is the primary goal. If a sanitize operation is interrupted (e.g. the disk is power cycled) then after power up any remaining user data will not be available and the sanitize operation will continue. When a format is interrupted (e.g. the disk is power cycled) the drafts say very little about the state of the disk. In practice some of the original user data may remain and the format may need to be restarted.

Finding out whether a disk (SCSI or ATA) supports SANITIZE can be a challenge. If the user really needs to find out and no other information is available then try 'sg_sanitize --fail -vvv <device>' and observe the sense data returned may be the safest approach. Using the --fail variant of this utility should have no effect unless it follows an already failed sanitize operation. If the SCSI REPORT SUPPORTED OPERATION CODES command (see sg_opcodes) is supported then using it would be a better approach for finding if sanitize is supported.

EXAMPLES

As a precaution if this utility is called with no options then apart from printing a usage message, nothing happens:

sg_sanitize /dev/sdm

To do a "block erase" sanitize the --block option is required. The user will be given a 15 second period to reconsider, the SCSI SANITIZE command will be started with the IMMED bit set, then this utility will poll for a progress indication with a REQUEST SENSE command until the sanitize operation is finished:

sg_sanitize --block /dev/sdm

To start a "block erase" sanitize and return from this utility once it is started (but not yet completed) use the --early option:

sg_sanitize --block --early /dev/sdm

If the 15 second reconsideration time is not required add the --quick option:

sg_sanitize --block --quick --early /dev/sdm

To do an "overwrite" sanitize a pattern file may be given:

sg_sanitize --overwrite --pattern=rand.img /dev/sdm

If the length of that "rand.img" is 512 bytes (a typically logical block size) then to use only the first 17 bytes (repeatedly) in the "overwrite" sanitize operation:

sg_sanitize --overwrite --pattern=rand.img --ipl=17 /dev/sdm

To overwrite with zeros use: sg_sanitize --overwrite --zero /dev/sdm

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