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merge(8)		    System Manager's Manual		      merge(8)

       merge - merge incremental dumps onto full dumps for restore

       merge <output file> <full dump> <incremental dump>

       merge is	a utility that allows one to apply incremental dumps to	a full
       dump and	produce	a new full dump	which reflects a later	state  of  the
       volume.	The new	dump can then be used to restore the volume, or	can be
       merged with other incrementals.

       An incremental or full dump reflects the	state of  the  volume  at  the
       time  it	 was dumped. Full dumps	can be restored	so that	a user may ac-
       cess an older state of a	volume.	Incremental dumps do  not  necessarily
       have  sufficient	 information to	be restored. For instance, all the vn-
       odes in the dump	may not	be present. The	merging	process	allows a  full
       image of	a state	that was only incrementally dumped to be restored.

       Currently  incrementals apply to	the last successful full dump that was
       done.  As an example, say full dumps for	a volume are done on  Sundays,
       with incrementals being taken the rest of the week. If an administrator
       wishes to restore a volume to Wednesdays	state, he would	have to	 fetch
       the  full dumpfile from Sunday and the incremental dumpfile for Wednes-
       day. Once these are present, the	administrator would use	the merge pro-
       gram  to	 create	 a new updated full dump for Wednesdays	state, and re-
       store it	to the server (using volutil(8)	restore).

       Information in the dump header is used to place a total ordering	on the
       dumps.  This  way  incrementals	can  only  be applied to the dump with
       repect to which they were taken.	In addition,  incrementals  cannot  be
       applied	to  other  incrementals,  and the dumps	to be merged must have
       been created from the same volume replica.  The	merge  program	checks
       these things, and reports failures if they are violated.

       volutil (8), restore (1)

       David C.	Steere,	1991, created



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