The relinking function can be run in the command or realtime mode. When the relinker command is run, it scans through the message store partitions, creates or updates the MD5 message digest repository (as hard links), deletes excess message files, and creates the necessary hard links.
The digest repository consists of hard links to the messages in the message store. It is stored in the directory hierarchy partition_path/=md5. This directory is parallel to the user mailbox hierarchy partition_path/=user (see Figure 20–1). Messages in the digest repository are uniquely identified by their MD5 digest. For example, if the digest for fredb/00/1.msg is 4F92E5673E091B43415FFFA05D2E47, then partition/=user/hashdir/hashdir/=fredb/00/1.msg is linked to partition/=md5/hashdir/hashdir/4F92E5673E091B43415FFFA05D2E47EA.msg. If another mailbox has this same message, for example, partition_path/=user/hashdir/hashdir/gregk/00/17.msg, that message will also be hard linked to partition_path/=md5/4F/92/4F92E5673E091B43415FFFA05D2E47EA.msg. This is shown in Figure 20–4.
The relinker process can also be run in the realtime mode for similar functionality. See 18.104.22.168 Using Relinker in the Realtime Mode for details.