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For each incremental backup
option is cleared. The backup is drawn as a green rectangle in the
figure.
The next three incremental backups are written onto tape 01 on 5th, 6th and 7th of January. As a
result the free space on the tape is only 16 Gb at the moment.
On 8th of January the data differential backup (40 Gb) is recorded onto the same tape 01, as the
Always use a free tape: For each differential backup
option is cleared. However the tape reached
the end after the first 16 Gb of the backup is written. Then the tape is dismounted and ejected from
the drive into a slot by the loader. Further, a free tape is loaded into the same drive and mounted,
and then the backup (last 24 Gb) is continued onto the beginning of the new tape.
The next figure demonstrates the data backup archive at the moment. The differential backup is
drawn as a blue rectangle in the figure. Number 1 in the green rectangle marks the incremental
backup created on Monday of the 1st week of the year.
Then the following backups are written onto tape 02:
four incremental and one differential backup on the second week
four incremental and one differential backup on the third week
four incremental backups on the 4th week.
The next full backup (320 Gb) should be written on Friday of the 4th week. However tape 02 has only
104 Gb of free space at the moment. So after the tape reaches the end, the recording continues from
the beginning of free tape 03.
Keep in mind, that the
Cleanup
task is launched after each backup operation for the GFS scheme.
This task deletes all the outdated backups. The next figure shows dark-gray rectangles instead of the
backups deleted up to the current time.
Physically the deleted backups are still on the tapes; however information about the backups is
deleted from the storage node database.
