Hi,
I have a fedora20 system that's currently serving about 500 mail users and is typically quite busy. I'd like to upgrade it to fedora22, but I also need to add more disks. This involves copying the data off the box and on to another one then back to this one after the new disks and OS are installed.

I'm wondering if anyone has a suggestion on how best to do this while limiting downtime? The services are http, dovecot, and postfix.

I'm thinking I could do something like this:

- rsync the data while the box is live to another machin
- Shutdown the production machine and do a final sync to the backup machine
- Set the IP of the backup machine to the production machine to minimize downtime
- Upgrade the disks on the original and reinstall the OS.
- rsync the data from the backup machine to the original machine with the new disks
- Shutdown the backup machine and do a final sync to the production machine
- Start the services on the production machine.

Does this sound like the most effective way? Any suggestions for creating a more fault-tolerant system for dovecot and postfix services?

I really haven't invested much on cloud technologies, but the demands are starting to exceed the capacity of any one box, and would like to find a way to distribute the email load across multiple machines as well as make them more fault-tolerant.

What technologies would I use for such a configuration? I've used drbd for disks in the past. Perhaps that's a viable option these days?

Thanks,
Alex

for skipping 21

full clean NEW install of 22

there are a lot of changes

you can "try" a inplace upgrade but i have never ever had one work on fedora

read the 21 and 22 change logs

for one fedora is deprecating "yum" ,22 uses DNF .

then in 6 months
reinstall with 23

the 6 month release and 13 month LIFE cycle is a bit FAST for a production mail server

You might think of using RHEL7.1 ( or CentOS)
RHEL7 has a 7 year life span


the 21 release nots for the big changes in 20 to 21
http://docs.fedoraproject.org/en-US/...tes/index.html

and the 22 notes for the BIG changes from 21 to 22
http://docs.fedoraproject.org/en-US/...tes/index.html

and read the "FedUP" page
https://fedoraproject.org/wiki/FedUp...lier:_Products
for upgrading 20 YOU MUST add a special command