The time it takes reconstruct to perform an operation depends on the following factors:
The kind of operation being performed and the options chosen
The number of folders when running reconstruct -m
The number of messages when running reconstruct -r
The overall size of the message store
What other processes the system is running and how busy the system is
Whether or not there is ongoing POP, IMAP, HTTP, or SMTP activity. Note that reconstruct is designed to run with the store services up. It is not necessary to keep the store offline to run reconstruct.
The reconstruct -r option performs an initial consistency check; this check improves reconstruct performance depending on how many folders must be rebuilt.
The following performance was found with a system with approximately 2400 users, a message store of 85GB, and concurrent POP, IMAP, or SMTP activity on the server:
reconstruct -m took about 1 hour
reconstruct -r -f took about 18 hours
A reconstruct operation may take significantly less time if the server is not performing ongoing POP, IMAP, HTTP, or SMTP activity.