IBM LTO Ultrium 4, Installation And User Manual

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WORM (Write Once, Read Many) cartridge
Certain records retention and data security applications require a Write Once, Read
Many (WORM) method for storing data on tape. The LTO Ultrium generation 3
and 4 drives enable WORM support when a WORM tape cartridge is loaded into
the drive.
Because standard read/write media are incompatible with the WORM feature, a
specially formatted WORM tape cartridge (see Figure 8) is required. Each WORM
cartridge has a unique, worldwide cartridge identifier (WWCID), which comprises
the unique CM chip serial number and the unique tape media serial number.
Type of cartridge Case color Native data capacity Recording format*
Ultrium 4 WORM Green and Silvery gray 800 GB (1600 GB at 2:1
compression)
Reads and writes data on 896 tracks,
sixteen tracks at a time.
Ultrium 3 WORM Slate Blue and Silvery
gray
400 GB (800 GB at 2:1
compression) Reads and writes data on 704 tracks,
sixteen tracks at a time
* The first set of tracks (sixteen for Ultrium 4 and 3; eight for Ultrium 2 and 1) is written from near the beginning of
the tape to near the end of the tape. The head then repositions to the next set of tracks for the return pass. This
process continues until all tracks are written and the cartridge is full, or until all data is written.
Data security on WORM media
Certain built-in security measures help ensure that the data written on a WORM
cartridge does not become compromised, for example:
v
The format of a WORM tape cartridge is unlike that of standard read/write
media. This unique format prevents a drive that lacks WORM-capable firmware
from writing on a WORM tape cartridge.
v
When the drive senses a WORM cartridge, the firmware prohibits the changing
or altering of user data already written on the tape. The firmware keeps track of
the last appendable point on the tape.
WORM media errors
The following conditions cause WORM media errors to occur:
v
Information in the servo manufacturer word (SMW) on the tape must match
information from the cartridge memory (CM) module in the cartridge. If it does
not match:
– a full-high tape drive will post a media Error Code
7
on the single-character
display (SCD)
a67b0024
Figure 8. Ultrium Data Cartridge on the left; WORM Cartridge on the right
Chapter 4. Using Ultrium media
39