On Tue, 2006-01-03 at 02:35, Hans Kristian Rosbach wrote:
There's always backup/mkfs/restore. If you aren't prepared to restore you should probably take care of that before worrying about efficiency.
Do you know how long time it would take to put back 800GB of mailboxes on our mailserver from the tape backup? No customers in the world would allow us to actually take such a time-off from serving their mail.
How do you plan to deal with an operator or software error that erases your current files?
Granted we COULD set up another box with a 1TB raid5 array to hold the data temporarily, but it would still take time since we would still have to shut down mail services before taking a copy. It would still be a bad workaround for a real problem. (Yes I know that ~99% of us don't ever need it)
You can do a swap like this with very little downtime if you do an rsync while the system is live to get most of the data copied, the repeat the rsync with the --delete option to catch any subsequent changes with the system offline, then swap mountpoints.
Thus we would need an on-line defragmenter that we could set up for a low-prio night run once or twice a year.
If you use maildir or other 1-message-per-file format, a defragmenter isn't going to help much because it won't know to move the directory contents together. If you have standard mbox format you just have to re-write them periodically which will happen anyway if the users ever delete anything.