HP Ultrium Tape Drive manual Glossary

Page 35

Glossary

AT&T mode

Berkeley and AT&T functional modes differ in “read-only” close functionality. In

 

AT&T mode, a device close operation will cause the tape to be repositioned just

 

after next filemark on the tape (the start of the next file).

Berkeley mode

Berkeley and AT&T functional modes differ in “read-only” close functionality. In

 

Berkeley mode the tape position will remain unchanged by a device close

 

operation.

BOT

Beginning Of Tape. The first point on the tape that can be accessed by the drive.

buffered mode

A mode of data transfer in write operations that facilitates tape streaming. It is

 

selected by setting the Buffered Mode Field to 1 in the SCSI MODE SELECT

 

Parameter List header.

compression

A procedure in which data is transformed by the removal of redundant information

 

in order to reduce the number of bits required to represent the data. This is

 

basically done by representing strings of bytes with codewords.

 

In Ultrium drives, the data is compressed using the LTO-DC compression format

 

which is based on ALDC (licensed from Stac/IBM) with two enhancements. One

 

limits the increase in size of data that cannot be compressed that ALDC produces.

 

The other is the use of embedded codewords.

data transfer phase

On a SCSI bus, devices put in requests to be able to transfer information. Once a

 

device is granted its request, it and the target to which it wants to send information

 

can transfer the data using one of three protocols (assuming both devices support

 

them): asynchronous, synchronous, and wide.

 

In asynchronous transfers, the target controls the flow of data. The initiator can only

 

send data when the target has acknowledged receipt of the previous packet. All

 

SCSI devices must support asynchronous transfer.

 

In synchronous data transfer, the initiator and target work in synchronization,

 

allowing transmission of a packet of data to start before acknowledgment of the

 

previous transmission.

 

In wide (16-bit) data transfer, two bytes are transferred at the same time instead of

 

a single byte.

 

HP Ultrium drives support asynchronous, synchronous and narrow (8-bit) wide

 

transfers.

Glossary

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Contents Generation 3 drives Version Date Changes Contents Verifying the Installation Documentation map Purpose of this manualRelated documents Documents specific to HP Ultrium drivesDrives-general Interface General documents and standardization How error correction worksIrvine, CA Tel 800 854 7179 or 714 261Page Introduction Backup ApplicationsIntroduction Ultrium Drives in a LibraryHP-UX AIX HP-UX Systems HP-UX SystemsHP Servers and Workstations-HP-UX Introduction Determining the Scsi IDSelect the following Creating the Device FilesFor an HP Ultrium drive, execute the following Where When you have exited sam, run ioscan to see the tape driveRun insf as follows To create a device file with the following characteristicsHardware path can be found from previous ioscan output For compressed mode defaultWhat Next? HP-UX Systems Add the following entry to your /dev/ddr.dbase file HP Alpha UnixHP Alpha Unix HP Alpha UnixWhat Next? This will produce output that looks similar to Configuring the Device FilesDetermining the Scsi ID Device Filenames under AIX Linux Configuring on Linux SystemsLinux Determining the Scsi ID LinuxThis should find a number of lines. One should look like Where /dev/stp is the device file Using the Seek and Tell Features of mtLinux This produces a list similar to Sun Systems, Solaris 8, 9Sun Systems, Solaris 8, 9 This will produce output similar to the followingLs -l /dev/rmt/*m grep st@X Determine the device file by typingHP-Data Values Do a reconfigure bootWhen the system is down, reboot Specifies the LUN for the device Values for the parameters for name are as followsSpecifies the Scsi ID target of the device Verifying the Installation Verifying the InstallationVerifying the Installation of the Drive Unix To verify the installationRead the file back from tape File The name of the file to archive, prefixed with ‘./’Extract the file from the tape Compare the original with the restored versionChange to the temporary directory Verifying the Installation Glossary GlossaryPoint-to-point connection between itself and the fabric Response to a filemark commandFibre Channel switching technology Features required by that standardGlossary Glossary AIX IndexIndex Index
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