My 10.6 Upgrade and OD Migration plan

Question

Hi, I wish to share my 10.6 upgrade/migration plan in order to get feedback/comments from people who may have insight/experience doing the same and thus be able to offer advice as to whether my plan is solid or if there's anything I should add/change and any potential pitfalls.
Background:
We have:
200 x clients
1 x OD/Mail/Firewall/PrimaryDNS/etc server - 10.5.8  (hereafter referred to as ODS1)
1 x File Server - 10.5.5 (hereafter referred to as FS1)
(current 80GB HDDs in these servers to be upgraded to 1TB)
Reason for upgrade is ODS1 causes all kinds of issues:
- OD seems to be corrupt (people sometimes can't log in, accounts can't be deleted in workgroup manager)
- Mail service only comes up sometimes at random intervals upon restart (i.e. sometimes takes half an hour, sometimes won't come up for a whole day or not at all.)
Unable to solve these issues and decided to upgrade this server to 10.6.7 in the hopes of solving problems.  We will also move OD to a separate virtual machine in the process - theory being that if OD has problems we can restart the server without affecting Mail and vice versa.
Restrictions on upgrade:
ODS1 is an XServe with two network cards (external and internal interfaces for Firewall) and Mail Store & User Directories is on Fibre Channel attached XServe RAID which means:
- I don't want to buy another fibre channel card so Mail Service has to remain on this XServe unless I move the mail store
- FW preferably to stay on here because this XServe has 2 network interfaces.
Luckily, very few users use the servers on the weekend so I don't have to worry about taking servers down for the upgrade.
Plan:
1. Prepare our new 10.6.7 Open Directory Master.  This will be a virtual machine running through Parallels Bare Metals on an XServe
Set hostname “ldap.ourcompany.com”.
Set static IP address
Install all the latest updates.
Set up as DNS master – import all entries, but change ldap.ourcompany.com to point to this machine.
Set up Open Directory Master with correct SearchBase, etc.
Disable any other services that we don’t need.
2. Export Users and Groups from ODS1 through Workgroup Manager
3. Import Users and Groups to new server through Workgroup Manager
3.5. Run script to set all passwords from our list  (Yes I have a list - and I know this is not best practice)
4. Test: by binding a new computer to this server and logging in with a user account set up on this server.
5. Backup
Make a backup copy of the new OD Master virtual machine.
On ODS1 and FS1, export all settings from Server Admin onto a thumb drive
Make an archive of Open Directory onto a thumbdrive (Server Admin -> Open Dir -> Archive Tab)
Copy from ODS1 onto some external HDD: Mail store and home directories locted on Fibre Channel attached storage
Run mailbfr –b /Path/to/backup/volume –full
Clone ODS1 HDD onto 1TB HDD using a caddy
Clone FS1 HDD onto 1TB HDD using a caddy
Remove HDD’s in ODS1 and FS1 and replace with clones and blank 1TB HDDs.
Implement new OD Master
6. Update ldap.ourcompany.com DNS entry to point to new server.
7. On ODS1, change Open Directory Role to Replica.[2]
8. On FS1, reconfigure Open Directory Replica.
9. On ODS1, change DNS role to replica and point tonew OD/DNS Master[3]
10. On FS1, change DNS replica to point to new DNS
11. On FS1, change DHCP to supply new DNS serveraddresses.
12. Test:
DHCP supplied LDAP on new computer.
Mail
Logging into accounts from existing computers
AFP
13. Backup again (so if next step fails we have at least achieved setting up new OD server)
Clone FS1 and ODS1 to blank internal 1TB drives.
Swap HD and Backup drive names and change start-up disk in System Prefs to newly named HD disk on both FS1 and ODS1, and restart, effectively testing the clones.
14. Upgrade ODS1 to 10.6.7
15. Change ODS1 DNS role to replica and point to newOD Master so that it has a working DNS service during the upgrade process.
16. Upgrade ODS1 to 10.6.7 in-place with CD
17. Check Mail settings before starting it.
18. Test:
Mail
Logging into accounts
Firewall
DNS Replica
VPN
Our Company custom scripts previously handled by Lingon (Any alternative to Lingon in 10.6?)
iChat
iCal
Software Update
WebMail
19. Point new OD Master’s Software Update to upgraded ODS1
20. Go Home!
Any advice?

Answer 1

Ok modified new plan, changes include:
- FS1 gets upgraded to 10.6 as well
- no "backup again" done - this will  never be a point we roll back seeing that 10.5 can't be replica of 10.6
- software update added
- clean installs rather than in-place upgrades so that we start afresh and hopefully not importing the many problems we were facing on 10.5
- other little changes
Everthing up to before the "Upgrade FS1" section is done in normal working hours while clients are using the servers and from then onwards, on a weekend.
Prepare our new 10.6 Open Directory Master virtualmachine
Set hostname to “ldap.ourcompany.com”.
Set static IP address 192.168.30.30
Install all the latest updates.
Set up as DNS master – import all entries, butchange ldap.ourcompany.com to point to this machine.
Set up Open Directory Master with correct SearchBase, etc.
Disable any other services that we don’t need.
Export Users and Groups from ODS1 through Workgroup Manager
Import Users and Groups to new server
Run script to set all passwords
Change Home Directories to “None” or if this fails, to a location on the local HDD.  (We use mobile accounts - ideally we need managed local accounts, nothing gets synced to server, so hopefully server home folders are not necessary - in 10.5 it didn't seem to work without having a server home set with a  directory full of empty folders.)
Change software update managed settings in Workgroup Manager to:   http://ods1.ourcompany.com:8088/index-leopard-snowleopard.merged-1.sucatalog This will only work after ODS1's 10.6 upgrade is complete
Test: by binding a new computer to this server and logging in with a user account set up on this server.
Backup
Make a backup copy of the new OD Master virtualmachine.
On ODS1 and FS1, export all settings from ServerAdmin onto a thumb drive
Make an archive of Open Directory onto a thumbdrive (Server Admin -> Open Dir -> Archive Tab)
Document all settings on ODS1 and FS1 by takingscreen shots of each pane in Server Admin and RAID Admin for easy referencewhen later setting up the new 10.6 ODS1.
On FS1, document all file shares and permissions
Copy from ODS1: /Volumes/Xserve User RAID and/Volumes/Xserve_Mail_RAID onto external HDD.
Copy from ODS1: /usr/bin/cyrus/bin/ to thumbdrive (required for migrating mail later)
Run mailbfr –b /Path/to/backup/volume –full
Clone FS1 and ODS1 HD drives to the internal BUdrives.
Make FS1 file shares backup (on separate XRAID)
Upgrade FS1
Remove HDD’s in FS1 and replace with 3 blank 1TB HDDs.
Install 10.6 from DVD.
Install latest updates.
Configure as per previously documented screenshots, but with the following changes:
Make it a replica of the new OD Master instead of ODS1
Add a secondary DNS zone pointing to new DNS server
Configure its DHCP to provide new LDAP server
Set all correct file share permissions aspreviously documented.
Test:
Attempt to connect to every volume with various different users to test that correct permissions are being applied.
Turn many client computers on to test if correct DHCP settings are received.
Upgrade ODS1
Do a fresh install of 10.6
Set up all services using documented screenshots, but OD and DNS will be replica instead of Master.
Migrate Mail store by renaming mail folder onthe XRAID to oldmail, then issuing this command:  sudo/usr/libexec/dovecot/migrate_mail_data.pl —moveMail 0 —cyrusBin "/Volumes/thumb_driveXXXX" --database "/Volumes/X-SERVE_Mail_RAID/oldmail/imap"--sourceSpool "/Volumes/X-SERVE_Mail_RAID/oldmail/spool/imap"--targetSpool "/Volumes/X-SERVE_Mail_RAID/mail/spool/imap/dovecot/mail"
Test:
afp://ods1.ourcompany.com./
Logging into accounts
Start up all computers in the office to makesure mail, managed prefs, DNS, DHCP, etc. work for all computers.
Firewall
DNS Replica by setting up a computer with staticIP
VPN
iChat
iCal
Software Update
WebMail
Point new OD Master’s Software Update toupgraded ODS1
Go Home!