BE 8.6 - Exchange Agent - Information Store vs. Individual Mailboxes?

[Chetty]

 What is the difference between backing up these two?  I read in another post that backing up both is copying the same information, just that you have the option to restore an individual mailbox if you so desire.  I have tried backing up both but noticed the information store is twice as big as the individual mailboxes.  If these are the same, shouldn't the sizes be the exact same, if not similar?  I believe our organization only needs to back up the information store, but we want to be sure we are getting everything.

Thanks in advance,
Chetty

[Ben_L_]

 I read in another post that backing up both is copying the same information, just that you have the option to restore an individual mailbox if you so desire

That is correct, the information is the same.  The only difference is that when you do a backup of just the information store it grabs the store(s) and all the logs.  This is probably where you are seeing the difference in size.  It also grabs all the hidden items that a mailbox backup won't do.  It is very normal for the backups of the information store and mailboxes to be different sizes.

[shirmal · Accepted solution]

 I would guess you are using 8.6 backup exec - due to the different size in the store and the mailboxes.. why..
Exchange stores uses Sngle Instance Storage - what this means is, if I sent an email with a 5 mb attached to 20 people on your Exchange server - Exchange will store the attachment once, then place a marker to the attachment in each mailbox assiciated with that message.

What happens when you back the message up- it will actually backup 100mb - because the backup extracts the same message for each mailbox.

Version 9.0 has Single instance storage backup - which is OK I guess, where it only backs up 1 the attachment once - the problem is with doing it this way, if that one attachment gets backed up corrupt, and you need to restore it, it will still be corrupt.

also, pschwarz - the limit of 16gb is only for Exchange Standard edition - if you get the enterprise version, it is unlimited - this was the same for 5.5.
There are other limits as well with the Standard edition, you can only have 1 Storage Group is the other thing I can think of.
Hope this helps

---cheers

shirmal