HP StorageWorks 6000 HP StorageWorks VLS and D2D Solutions Guide (AG306-96028, - Page 151

Data comparison, Data reassembly, level between backup objects.

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b. the names of the backup jobs c. the server being backed up d. the type of backup - full or incremental e. the type of data in the backup - files, database, etc. The deduplication software then queries the metadata database to find an equivalent older version of the same backup job to compare it against the new backup. If the current backup is full, it will be compared against the last equivalent full backup version. If the current backup is differential or incremental, it will be compared against the next equivalent full backup version (TSM "incremental forever" backups are all treated as full backups by deduplication). 3. Data comparison This phase is also called delta differencing. After the data grooming phase is complete, and if there is an older version of the backup, either full or incremental, the new backup is compared, or delta-differenced against it. The deduplication software looks for differences at the byte-level between backup objects. 4. Data reassembly In this phase, duplicate data is replaced with pointers, and pointers are readjusted so that they point to the most recent instance of data. If the new backup is a full backup, this phase does not touch the new data, so that the most recent backup is complete and available for restores. Instead, a new copy of the older version is created. See Figure 68. If the new backup is incremental, it is reassembled so that duplicate data is replaced with pointers to the last full backup version. HP StorageWorks VLS and D2D Solutions Guide 151

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b.
the names of the backup jobs
c.
the server being backed up
d.
the type of backup
full or incremental
e.
the type of data in the backup
files, database, etc.
The deduplication software then queries the metadata database to find an equivalent older version
of the same backup job to compare it against the new backup. If the current backup is full, it will
be compared against the last equivalent full backup version. If the current backup is differential
or incremental, it will be compared against the next equivalent full backup version (TSM "incre-
mental forever" backups are all treated as full backups by deduplication).
3.
Data comparison
This phase is also called delta differencing. After the data grooming phase
is complete, and if there is an older version of the backup, either full or incremental, the new
backup is compared, or delta-differenced against it. The deduplication software looks for differ-
ences at the byte
level between backup objects.
4.
Data reassembly
In this phase, duplicate data is replaced with pointers, and pointers are
readjusted so that they point to the most recent instance of data.
If the new backup is a full backup, this phase does not touch the new data, so that the most recent
backup is complete and available for restores. Instead, a new copy of the
older
version is created.
See
Figure 68
.
If the new backup is incremental, it is reassembled so that duplicate data is replaced with pointers
to the last full backup version.
HP StorageWorks VLS and D2D Solutions Guide
151