Clean install OSX+S 10.9 then migrate data from 10.6 Server?

Question

Howdy All,
I've had OSX Server from the first release but stopped at Snow Leopard Server waiting for the "new server" to mature a bit.  I think it is time now to move to OSX Server 10.9 but also for a clean install to clear out the crud that has collected over all these years. 
I have two main partitions: one for the OS with the Mail store and Wikis and another for user home directories and other files.  Again this is going from Snow Leopard Server 10.6.last to 10.9 Mavericks and then Mavericks Server
My question is:  If I clean install Maverick and then Mavericks server on another partition will I be able to migrate data and services over manually? 
Of course, I will need to setup users and directory services again from scratch (but that is part of the plan to clean out the unused stuff that has collected over the years).  I don't mind setting up fileshares, Web sites, DNS, and similar again.
However, when this is done will I be able to copy the mail store (i.e. all users email) over and will it be detected, updated if needed, and work?  Similarly, when I copy over the wikis, will they be detected, updated if needed, and work?
Further, when I setup the symbolic links for home directories again (onto the other partition), will the home directories be updated (if needed) and work?  I'm not sure what could have changed with regards to home directories but you never know.
In summary, I guess my question is about what migration only happens when you update as opposed to what happens when an older version of a resource or service is detected after an update.  Hopefully there is more of the latter than the former. 
Thanks in advance for any thoughts on this.
Cheers,
Ashley.

Answer 1

Out of your services (AFP/SMB, Mail, OD, SWU, and web), the one with the most potential for disaster and headache is clearly mail.  If you are using the same host device, cutting services over in pieces will not be possible.  However, here are some suggestions and potential points of concern.
AFP/SMB file services are cake.  The only thing you need to consider is the potential time to copy the data if you are moving it to new disks.  The other issue will be user's GUID values and the associated ACLs.  Let's take the following scenario based on what you've detailed.
• You have data on /HDD/Shares/ and you are planning on moving them to the SSD.  Is the SSD drive large enough to accept this data? 
• If you had a share /HDD/Shares/Data and this contained an ACL allowing the design group to have access, the design group from the 10.6.8 OD may have a different GUID than the one you create on the 10.9.1 system.  If this is the case, you can purge all ACLs with a sudo chmod -R -N /path/to/data.  (Server.app should remove and then add but older versions resulted in merged messes so I go nuclear on the old settings)  Then you can apply your new ACLs and allow the permissions to propagate.
• If you are leaving the data were it is, you will simply need to reset permissions.  However, note that if you are exporting and then importing users (via an OD backup or via standard record format) then you are maintaining GUID and should not need to touch any permissions.
Regarding SWU, I would suggest looking into Caching server.  If you are moving the entire environment to 10.9 and iOS 7, SWU is no longer needed.  Caching server is easy as pie, requires no client configuration, and is more economical on your internet connection and server storage requirements.
Web is pretty easy also.  But, this is dependant on what you are doing with web.  If html/php/perl then you pretty much just move your site folders and you are up and running.  If you were using MySQL, note that Apple replaced it with Postgres.  You can either perform a conversion from MySQL to Postgres or you can just install MySQL again manually.  The choice is yours.  If you are not doing database backed sites, the migration should be cake.
OD is one of those technologies that I always prefer to start clean.  In really large environments, this can be very tough due to passwords.  You can export an OD backup from 10.6 and attempt a restore in 10.9.1.  If you have a lot of MCX in 10.6.8, you may run into some trouble as Apple has deprecated MCX in 10.8 and above.  However, this ensures that you have everything, from password to GUID.  Test, test, and test some more if you go this route.  An alternate option, especially if you are embracing the move away from MCX and to Profiles, is to do a user and group export for 10.6's Workgroup Manager.  This will not provide passwords but it will provide editable text files of your account data.  You can strip out the MXC and other legacy values and then use the resulting file to import users into a clean 10.9.1 OD master.  Once again, you will not get passwords unless you add them to the import file.  You need to figure out how many accounts and how sensitive users are to password resets.
The final piece is mail.  This is the one area I have very little experience.  I've been burned by Apple's mails solutions from way back in the AppleShare IP days and now make it policy to use anything else but Apple's mail solution.  In a perfect world, moving the mail data store to the new OS and triggering Server.app should be enough.  But Apple + mail never seem to enter the realm of a perfect world.
And finally, make sure DNS is correct before you do anything.  Since you are dealing with mail, you should also shut firewall port forwards to prevent new mail from coming into the server while you work on the migration.  Nothing worse than stitching mail together after a blown migration attempt.
R-
Apple Consultants Network
Apple Professional Services
Author "Mavericks Server – Foundation Services" :: Exclusively available in the Apple iBooks Store