Blog Post: Understanding Exchange Server 2013–Part2 (Public Folders) #Microsoft #msexchange

Public Folders provide an awesome way for collaboration, for years there were rumors that Microsoft will drop PF with the introduction of Exchange 2007, Microsoft saw obstacles in PF as they are using different management and different hierarchy and architecture from regular mailbox.

With the introduction of Exchange 2013, Microsoft made PF leaps into the future with the changes that Microsoft introduced on PF storage in Exchange 2013, so what happened to PF in 2013, let us take a look:

• PFs are not stored in PF mailboxes: previously PF were stored in the PF database, thus prevented the use of modern protection technologies offered by Exchange 2007/2010 such as replication/DAG, in Exchange 2013 PF are now stored in special type of mailbox called a PF mailbox, this mailbox stores the PF hierarchy and the PFs content that were created on that mailbox.
• PFs no longer utilize PF replication architecture: In previous versions of Exchange PFs were utilizing the PF replication architecture, it was a separate architecture that was managed separately and required its own set of monitoring and management and was inherited from previous versions of Exchange, with the new architecture PFs no longer use replication as before, the mailbox itself can be replicated now using DAG architecture offering mailbox resiliency and protection, but content themselves are not replicated across mailboxes, each content mailbox holds his own content and he is the only holder of that content, the mailbox is replicated using underlying DAG architecture but not the content.

With the new architecture we have now a new type of mailboxes called “Public Folder Mailbox” this mailbox can be divided into 2 types:

1. Master Hierarchy PF Mailbox: the Master Hierarchy mailbox is special kind of PF mailbox that you create to either import your hierarchy from previous versions or and hold your PF hierarchy and this is usually the first PF mailbox you create.
2. PF mailbox: All later PF mailboxes are that kind of PF mailbox, there is a very important difference between PF mailboxes and Master PF mailbox, the Master PF mailbox holds a writable copy of the hierarchy but other PF mailboxes hold a read-only copy of the hierarchy (note: you can upgrade a PF mailbox to a master one anytime, but at any time there is only 1 writable copy of the hierarchy) (another note: all PF gets a copy of the hierarchy but it is read only one)

Design Considerations:

with the new architecture there is a very important point to note (PF contents are not replicated) so organizations that are geographically dispersed and utilizing PF replication to provide local access to Public Folders must reconsider their PF hierarchy and how it is planned now because in order for a user to access the PF content he will need to access the content PF mailbox directly and that might occur over the WAN if content distribution is not well planned.

For the last point some people might have some concerns, but with the all HTTPS traffic between clients and CAS I can imagine that with the use for WAN optimizers and proper planning this will offer orgs greater flexibility and even better management.

From end-users perspective, PFs in Mailboxes are just the same as PF in older versions of Exchange, the storage of the PF is different from admin point of view but users are not aware of that change

The other things you might want to consider is the PF mailbox storage limit, mailbox in Exchange 2013 supports 100 GB, although it is fine for normal mailboxes, you will need to take serious consideration if your organization is heavily using PFs and you have PF trees that is larger than this limit.

The only things that you will need to know that RTM launch, PF will be available from Outlook Only, OWA access to PF is not ready yet.

at this point and as this article is being written any of the secondary hierarchy mailboxes could be prompted to a primary one, but this is not documented until now, I will update this article to include a pointer for the new information, to identify which mailbox is the master hierarchy mailbox you can use this cmdlet:

Get-OrganizationConfig | fl DefaultPublicFolderMailbox

PF Migration from earlier versions:

As this article is being written Exchange 2010 SP3 is the only source from where migration  can be done, Exchange 2007 is supported for coexistence with Exchange 2013 but an update that is unknown so far will be released later to allow such coexistence.

The migration high-level steps are done as following:

• You Generate a CSV file that contains your hierarchy from your older Exchange server. Keep in mind that you can open that CSV and edit its content mapping to PF mailbox if you would like to spread your content across mailboxes for geo-access or for proper distribution.
• You create a Master Hierarchy PF mailbox and import that CSV to it.
• Create a new PF migration request.
• Lock down the access to the PF, at the final stages a lock down is placed which prevents users from accessing the PF to lock access to finalize the migration.
• Complete the request and resume the migration.

the steps are detailed here http://technet.microsoft.com/en-us/library/jj150486(v=exchg.150), once lab is done I will post a blog post about editing the CSV before migration.

I hope that you enjoyed the post and wish you happy Public Foldering .

Mahmoud