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NetWin Database Mode
Enable using: g_maildir_netwin "true".
Warning! This feature is in Beta test stage, we have run it ourselves for several months and have had no problems. We haven't heard from any customers about any problems either. We would definitely recommend keeping a backup(as you should anyway) if you decide to go with this method or running a mirror that is using the old/standard maildir method.
How it works:
storing each mail message as an individual file messages are stored in
'bucket' files which contain many messages, an index file contains a list
of the contents of all of the bucket files.
So a folder
with 100 mail messages in it might look like this:
05:15 p.m. 1,120 bkt.idx
28/09/2005 05:15 p.m. 0 bkt.lock
28/09/2005 05:15 p.m. 7,578 bkt_0.bkt
28/09/2005 05:15 p.m. 4,450 bkt_0.head
26/09/2005 05:09 p.m. 442,871 bkt_1127711348.bkt
26/09/2005 05:08 p.m. 31,668 bkt_1127711348.head
When a bucket
file is partly empty due to deleted messages it is re-written.
always go to bucket zero.
What advantages does it have
- When accessing
lots of little files the disk IO is greatly reduced, and the speed can
thus be 2-4 times faster.
- IMAP gets
the most noticable speed improvement.
- When backing
up a mail partition the operating system has a much simpler job, this
can make backup runs 4-14 times faster.
- Some operating
systems either fail completely, or run very badly when a disk has millions
of files on it, this reduces this problem drastically.
- If sharing
a drive using NFS it should work as long as fcntl locking works on your
What disadvantagese does it have
- It's a new
feature which involved massive internal changes to surgemail, there is
significant risk that bugs could exist in it.
- It is a
lot more complex than the 'file per message' model, so is more prone to
- You can't
manually examine a users mail box and modify files (although there are
some commands to let you do this to some extent)
delivery is about 20% slower! (as the indexes are written at delivery
How do I turn it on ?
- Make a backup
of your mail spool (or mirror it)
- Set the
new setting g_maildir_netwin "true"
- An automatic
conversion process will start, in addition any mailbox which is accessed
will be automatically converted.
- (You can
turn it off the same way, change the setting and restart surgemail)
- DO NOT DOWNGRADE
TO AN EARLIER VERSION OF SURGEMAIL AFTER CONVERTING :-)
- You can
turn it on, on ONE member of a mirrored pair of surgemail servers.
dir user@domain [folder]
files in that inbox/folder
ndb_export user@domain foldername destination_path
files to a directory
index based on bucket files
convert process again