User manual

Using S.M.A.R.T. Disk Monitor 51
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Do you want to assign a custom (non-zero) defect list format or assign vendor-unique settings? <Y/N>: N
Are you sure you want to do this? Answer "YES" to begin the low-level format, anything else exits program:
YES
Sending command .... This will be last text you see until format complete or rejected.
Formatting ... [This is where the cursor will stay until format complete] completed ... Program terminating.
Command Options
Once you see the warning message after you invoke this command, you will be given the opportunity to select some
additional features which must be defined before the format command is sent to the disk drive. The reason is these
additional functions can only be performed on a disk at the time you format it. This is not a SMARTMonUX limitation.
These constraints are within the ANSI SCSI specification.
Do not combine the -format command with any other options. As this feature is destructive, it may not be run in
batch mode, and requires you to enter YES before the program begins reformatting your disk drive.
You may add the -confirm command which will suppress the are-you-sure. We strongly recommend you only use
this in a batch test environment where you know exactly what you are doing. You will not be able to stop the process
once you press return.
Clear Grown Defects
Disks typically (but not always) maintain a list of factory (called primary defects, or PLIST) and grown defects, called
the GLIST. There may also be a DLIST. The primary defect list is created at time of manufacture and cannot be
altered. The GLIST is built after time of manufacture and grow as either the disk detects areas as data is written, or
the operating system detects a problem with an area of the disk and reassigns the data to another location.
SMARTMonUX allows you to clear the grown defect list at the time you format the disk, or more correctly, allows you
to turn on this feature that is inherent in the disk drive, when the SCSI command to reformat is sent to the disk.
Ordinarily you would rarely want to clear the grown defects, as they are built over time whenever the disk detects a
bad area of the disk and decides data should not be kept there. If you clear the defect list then you run risk of data
loss when data is written to a bad sector that is not marked as bad. We will not editorialize further on the merits of
clearing the GLIST and suggest you contact your storage vendor to determine whether clearing the GLIST is
something you need to do. We will say that the only time we ever clear the defect list is when we reformat the disk to
use a different sector size, and we follow the operation with a program that fully exercises every sector in the disk to
properly rebuild the GLIST before any live data is put on the drive.
Specifying the Defect List Format
The ANSI specification allows for numerous formats that the defect lists can be presented to a program when it sends
the appropriate SCSI commands to retrieve the data. Basically you have vendor unique, bytes-from-index, and
physical sector format. Ordinarily you would take the defaults, format 0, which is mandatory per the ANSI spec for all
disk drives. This might not be the correct format for drives that have special OEM firmware on them or are placed
behind some RAID controllers. If you do not know what format to use, ask your storage vendor.
Formatting Disk with Full Parameter Control
SMARTMonUX provides the user a mechanism to specify the complete SCSI CDB. This allows you to do anything
from force a certain interleave factor to provide custom defect layouts or even pass vendor/drive unique commands to
the disk to perform tasks that are only documented under customer/vendor non-disclosure agreements. If you need
to format your disk with non-standard parameters, answer Y to the "Do you want to assign a custom
(non-zero) defect list format or assign vendor-unique settings" question. You would then see:
Do you want to assign a custom (non-zero) defect list format or assign vendor-unique settings? <Y/N>: y
Please enter the last 5 bytes of the FORMAT UNIT CDB in hex. If you don't know what they
should be, then it is highly probable you should NOT be sending vendor-unique info.
CDB[0] = 04
CDB[1] =
You would enter the hex byte for the 2nd CDB byte and continue the process until all 6 bytes of the SCSI CDB were
filled in. The reason the first byte of the CDB is 04 is because that value represents the op-code to perform the
FORMAT UNIT command, so that would not change. After all 6 bytes have been entered (red represents what the
computer displays, blue is what the user typed in this example), the format would begin provided you entered YES