Exchange: the recovery storage group

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Today we are talking about retro-software... As many of you are already using Exchange 2010, you might not be interested in the information given in this post. In fact the Recovery Storage Group has been removed from the Microsoft famous email server starting from the 2010 version.
Anyway, if you are sticking with a previous release then I believe you should - at least - know something about recovering mailboxes from a backup. In my experience, whenever I knew about a possible disaster recovery solution, the disastrous situations never occurred. It's like a protective talisman!
So, here we are. Read this post and take it as an amulet, protecting you from disastrous situations!

What is the Recovery Storage Group?

The Recovery Storage Group (RSG) is a storage group (!) that can be used to mount a backed-up copy of a mailbox store in your Exchange environment.
Typical situation:
1) Your Exchange is working and should continue to work;
2) You need to recover a deleted mailbox or single email;
3) You do have a back-up copy of the mailbox store;
4) You need to recover that back-up and put it in a safe position to extract mails with ExMerge.
Confused? You shouldn't, because the operation is quite easy - even if could be quite time consuming.

Create the Recovery Storage Group

The operation is similar to creating a normal storage group:
1) Select the server object;
2) Right click on it;
3) Select new/Recovery Storage Group.
Don't be afraid, The whole procedure won't affect the normal working operations of the main storage group(s). When a properties dialog appears, just fill in the appropriate information and click ok.
You will then see that inside the server object tree menu, you have the usual folders (protocols, queues). Between them you can see the First Storage Group (your mailboxes are safe there) and - presto! - the Recovery Storage Group.
Now this is very important: if you open the properties of the First Storage Group, at the bottom of the Database tab you can see "This database can be overwritten by a restore". IT IS VERY IMPORTANT that the checkbox is NOT ticked there. Again: DO NOT SELECT THAT OPTION IN THE FIRST STORAGE GROUP.
Why is that? When we are going to recover the back-up, we definetly don't want to overwrite the First Storage Group (or other groups).

The mailbox store

After that, we need to create the mailbox store for the Recovery Storage Group. Right click on it and select Add Database to Recover. From the opening dialog, choose the appropriate database to recover. If you have only one Storage Group (apart from the Recovery one), you will have only one option.
After that, a new property dialog pop-ups. That is the property dialog of the mailbox store. Here you will see that - at the bottom of the database tab - "This database can be overwritten by a restore" is ticked. In this case we need it to be that way (because we need to overwrite the store with the backed-up data).
At this point, do not mount the mailbox store.

Restore the backup

For the moment, we are done with the Exchange System Manager. Now we need to recover the back up.
Open Windows backup utility and use the recovery wizard to recover your back up. Locate your .bkf file and restore it. Now you might wonder if that procedure will overwrite your First Storage Group. No. It will not. Exchange and the backup utility work perfectly together and the backup utility will automatically detect the Recovery Storage Group and it will recover the mailboxes there.
Depending on the size of your store, the recovery will eventually be completed. During it, you can see the files growing in size inside the Recovery Storage Group folder.
When the process ends, you can mount the mailbox store.

ExMerge

You may remember I talked about ExMerge. Now it is time to use it. Please refer to this post for more information. Here I will only point out that during the configuration of ExMerge operations, you will be offered the option to choose between different databases. At some point, you can select which storage group to use. In our situation, we need to use - guess what? - the Recovery Storage Group

Some notes

The Recovery Storage Group is very usefull in different situations. It is not a solution for disaster recovery, because - as you may guess - there would be no Exchange Server to work on. However it is indeed a viable solution when you need to recover partial information from a backup.
Now that you know how it works, you will probably won't need it. But just in case...