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NetBackup System Administrator’s Guide - Windows NT Server
B
Where:
MH = Media Header (1024 bytes)
* = Tape Mark
BH = Backup Header (1024 bytes)
Image = Data from the backup
EH = Empty Backup Header, used for position validation.
When adding a new backup to the above example, the tape is positioned to EH
and position is verified. The EH is overwritten by a BH and the backup
proceeds. When complete, a new EH is written for future positioning
validation. When NetBackup encounters the end of media during write, it
terminates the tape with two tape marks and does not write an EH.
For the multiplexed format, see “Multiplexing Format” on page 447.
QIC Tape Format
For QIC tape media, NetBackup does not write empty backup headers (EH) so
the format nonmultiplexed backups is:
MH * BH Image * BH Image * BH Image . . .
To append backup images to QIC media, NetBackup positions to the end of
data (EOD) and then starts the next backup.
For the multiplexed format, see “Multiplexing Format” on page 447.
Fragmented Backups
For fragmented backups the media format is the same as described for QIC
and non-QIC tapes, except that NetBackup breaks the backup into fragments of
the size that you specify when you configure the storage unit.
For example:
MH * BH1 Image (frag 1)* BH1 Image (frag 2)* BH1 Image (frag n) * EH *
Fragmentation is intended primarily for storing large backup images on a disk
type storage unit. In these instances, fragmenting images allows you to avoid
exceeding the two gigabyte size limit that applies to most UNIX file systems.
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT
