We are on 2007 and looking to move to 2013. Our current mailbox storage totals ~5 TB. Since the sizing spreadsheets are not available for 2013 yet, I need some guidance. I'm planning for 3 MBX servers in our main site, and 3 in our DR site all in the same DAG. Each MBX server would serve one active mailbox DB and have 4 passives and one LAG = totaling 6 DB's. This follows the equally distributed model. My questions are around the sizing of the LUN's to support these DB's. 1. Would 850 GB DB's be an issue? The few resources I can find indicate this should not be. 2. I'm assuming there isn't a problem with multiple LUN's so that the actives, passives and lag DB's can be on their own LUN's. Correct? Thanks...

1. No. The size limitations on databases are really high now, but it's typically a good practice to have lots of smaller DBs rather than a single huge DB, since having a large DB can cause a lot of resources getting burned up on indexing, and the larger DBs take significantly longer to perform repair and offline Defrag operations on if necessary. Repairs aren't as necessary with DAGs, but if you ever want to clear white-space in an 850GB DB, it can take a very long time to complete that operation. 2. There are no problems with using multiple luns. Once the LUNs are connected to the server, they just show up as Drives and that's all Exchange cares about.

Hi,mcmckuf, 1.No,but I would recommend you to use smaller databases to avoid some performance or secuirty issue. 2.Correct.Actually the recommend option is a single large LUN host a single database and log file. Regards, SharonSharon Shen TechNet Community Support ************************************************************************************************************************ Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question.

Thanks for your answers. Could you clarify something for me? We can't find anything regarding the indexing with FAST on 2013. Is this just in with the DB's like 2007? Is the size significantly larger? Regarding the DB size, we are just thinking we wouldn't even try offline defrag. Just move mailboxes and abandon the DB. Our experience has been poor with 2007 and performing those options with great success. Appreciate it, -M

Hi Sharon, Thanks for your answers. Could you actually clarify what you meant by performance or security issues? For Performance, we are going with separate RAID 10 LUNs for each DB and Log drive. OS will be in on RAID 6 using VMware with dedicated hosts. I didn't know what you meant by security. Thanks... -M

Offine Defrag does the exact same thing as moving mailboxes to a new database, so your plan to use that method is perfectly acceptable. Just requires no downtime :D If you're asking about FAST Indexing on Public Folders, that wouldn't be necessary with 2013, since Public Folders are stored as mailboxes rather than a separate database now. As a result, Public Folder indexing happens along with the normal functions of Mailbox indexing that happens with Exchange.