Am 06.08.2013 21:26, schrieb Leonardo Rodrigues:
> After syncing the folders with services stopped and configs already pointing 
> to the new places, it would be
> just a matter of getting services running again !
> 
> Downtime of maximum 3-4 minutes !!!
> 
> But watch out ... these steps would make sense only if you're using Maildir 
> mailbox format ... if you're using
> mbox, for example, syncing times would be much longer as any change would 
> require the whole file to be copied again!!

no - rsync does *not* copy whole files again

it copies only the changed parts and it is very
unlikely the a mbox fil eget changed at whole

this works even for virtual machine images where you get displayed
transfer rates up to 200 MB/second over WAN and the same for large
innodb files
____________________________________

http://rsync.samba.org/how-rsync-works.html

Then the local file is read and a checksum is generated for the block beginning 
with the first byte of the local
file. This block checksum is looked for in the set that was sent by the 
generator, and if no match is found, the
non-matching byte will be appended to the non-matching data and the block 
starting at the next byte will be
compared. This is what is referred to as the “rolling checksum”

If a block checksum match is found it is considered a matching block and any 
accumulated non-matching data will be
sent to the receiver followed by the offset and length in the receiver's file 
of the matching block and the block
checksum generator will be advanced to the next byte after the matching block.

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