In this Technote IBM warns using “compact -replica” during online mode !!

Compact -Replica lose document data if user modify the document during compaction.

Steps to reproduce:

1. Prepare discussion database

2. add about 10 documents with attachment (attachment size is about 1MB – 4MB). In my test. doc # is 10 and db size is 53MB.

3. Keep the database open by Notes client and perform “load compact -replica xxx.nsf”.

4. If you see the following console output, Update any document’s title right away.
>drop xxx.nsf

5. Compact -replica fails with the following error.
> Error compacting disc.nsf,  -replica disc.nsf: Database is
currently in use by you or another user

6. Add a document and add any attachment.

7. Close the database.

Repl file is remains. nsf file is bigger than repl file because
I add a document with a big attachment.

8 Open the database again by Notes client. In Domino Server, it will start compact -replica -restart will perform automatically. However it will fail with the following error.
>Compact -REPLICA sync failure, Src DB:
C:\Lotus\Domino\data\disc.ORIG, Dst DB:
C:\Lotus\Domino\data\disc.nsf : Specified database is not currently open

9.Close the database.
Orig file is remains.  nsf file size become small.

10 Open the database again by Notes client. In Domino Server, it will start compact -replica -restart will  perform automatically. At this time, compact perform completely..
Orig file is deleted. nsf file size is still small.

Whenever user update document in step 4 and  add a document in
step 6,  all changes lost by compact -replica.