dovecot - Feb 2014 - version question

I have Dovecot server from a iRedMail install, version 2.0.21

dovecot --version
2.0.21

yum update wants to update as so from iRedMail repo:

--> Running transaction check
---> Package dovecot.x86_64 1:2.0.21-0_136.el6 will be updated
---> Package dovecot.x86_64 1:2.1.17-0_136.el6 will be an update
---> Package dovecot-managesieve.x86_64 2:0.2.6-22.el6 will be updated
---> Package dovecot-managesieve.x86_64 2:0.3.6-26.el6 will be an update
---> Package dovecot-pigeonhole.x86_64 2:0.2.6-22.el6 will be updated
---> Package dovecot-pigeonhole.x86_64 2:0.3.6-26.el6 will be an update
--> Finished Dependency Resolution

 Package                       Arch             Version                   
     Repository          Size
========================================================================================================Updating:

 dovecot x86_64 1:2.1.17-0_136.el6              iRedMail           2.4 M
 dovecot-managesieve x86_64 2:0.3.6-26.el6      iRedMail            45 k
 dovecot-pigeonhole x86_64 2:0.3.6-26.el6       iRedMail           348 k


so, if I run this update, I'll update to '2.1.17-0', yes ?

ahem, dumb question ahead: what's the '1' in front ? 1:2.1.17-0_136

(dumb user worrying that I don't attempt to install ver 1...)

apart from /etc/dovecot/*, should I backup anything else ?

sorry for dumb q...

thanks

On 02/21/2014 11:37 PM, voytek at sbt.net.au wrote:
> --> Running transaction check
> ---> Package dovecot.x86_64 1:2.0.21-0_136.el6 will be updated
> ---> Package dovecot.x86_64 1:2.1.17-0_136.el6 will be an update
> ---> Package dovecot-managesieve.x86_64 2:0.2.6-22.el6 will be updated
> ---> Package dovecot-managesieve.x86_64 2:0.3.6-26.el6 will be an update
> ---> Package dovecot-pigeonhole.x86_64 2:0.2.6-22.el6 will be updated
> ---> Package dovecot-pigeonhole.x86_64 2:0.3.6-26.el6 will be an update
> --> Finished Dependency Resolution
> ahem, dumb question ahead: what's the '1' in front ?
1:2.1.17-0_136
>
>
As you can see the 1: prefix appears also in your currently installed 
packages.
The number followed by a colon, e.g. 1:, is not part of the upstream 
version, it's called an epoch and it's part of the package version.
It's
a trick related to your package manager and its repositories, not to the 
specific software in question.