1.3.3 Backup strategies

There are virtually an infinite number of ways to integrate UPSTREAM into your backup strategy. The merge backup facility is the easiest to use and the most powerful.

Merge backups allow the UPSTREAM client system to send a fraction of the total data on a disk (only slightly more than an incremental backup) and still end up with a complete full backup.  Using a sophisticated technique, the client system sends a “picture” of the drive(s) to be backed up to the Reservoir software which uses prior backups plus changed files to construct the fulls.

Advantages:

  • A full backup is created with the UPSTREAM client only having to send a tiny fraction of the total data.
  • Easier to use, understand and manage.  The beauty of a merge backup is that all the complexity is behind the scenes; it is actually as easy or easier to use than non-merge backups. 
  • If you are using tapes for incremental backups, you use fewer tapes.

A single backup profile name is used for full and incremental backups.  It is recommended that this single profile represent a single, unchanging group of file specs (a single server, a single workstation disk, etc.).  The facility is flexible enough for you to be able to add or remove drives, however it is not recommended that you use a profile for more than one entity.

The technique requires that you perform a first-time baseline full backup of the file specifications that you wish to maintain.  In this backup you do transmit all the files.  Once you have this full backup, you only perform incremental merge and full merge backups. 

Incremental merge backups are backups where only the changed files are transmitted to the UPSTREAM server.  The first incremental merge backup after a full backup begins a new tape or disk file; subsequent incremental merge backups to tape can be appended to previous incremental backups.  Subsequent incremental merge backups to disk create new server disk files.

Full merge backups are appended to the end of the incremental backup file (if the backup is on tape), or a new file is created (if the incremental backups are on disk).  The UPSTREAM client sends all the changed files as well as the directory entries for all files which it does not believe have been changed.  The UPSTREAM Reservoir then examines this list of files, retrieves from old backups (the last full or any of the prior increments) files which haven’t changed, and requests from the UPSTREAM client files which it doesn’t have. 

Before UPSTREAM will use a file from a previous backup, it will verify a match of the complete, qualified file name, the last modified date and time, and the file size.  If any one of these conditions do not match, the UPSTREAM server software will request a transmission of the file from the UPSTREAM client.  The result is a complete full backup without the UPSTREAM client software having to read or send the vast majority of the data, and deleted files are properly reflected.

Note that merge backups will not be of help in certain database, software or hardware environments (Oracle, DB/2, VMWare, NDMP, etc.).  See the UPSTREAM Client User’s Guide for a description of environments where the merge is inappropriate.

The following scenarios should help you understand the process.


 

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