Recover from the loss of an Exchange DB.

bmcollis
bmcollis used Ask the Experts™
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Recover from the loss of an Exchange DB.

I have lost an Exchange 2010 Database, without going into it, I have no backup.

The question is how to recover from this situation.
About 20 users.  DB Size approx 200GB
All users of their email in OST files on there PC's.
Exchange is running in a Hyper-V Guest
Have access to the DB Files.

Believe that an underling disk error, on the host, corrupted the DB.
(as a side not - and not that it matters to getting this issue fix, believe the disk was the cause for the backup failures, hence no backup)

Thinking - Create a new DB on a different physical disk.
Move the users to the new DB - is this possible if the original DB cannot be mounted?

So apart from - is this a good way to go - the other questions are;
Do I need to do anything with outlook for the clients to connect to the new DB?
As their mailboxes would be empty in the new DB, will outlook sync the OST file contents back up to exchange?

If the OST wont sync, should I convert them to PST and then manually attach the PST to the Outlook Profile and them move the email into the empty DB.

I appreciate any any scenario I will loose single instance store and therefore the DB will end up larger than the original.

Has anyone used/got thoughts on - using 3rd party exchange DB recovery software?
if it can't recovery everything, then again will the OST sync up the missing emails or are they gone?


Any suggestions help would be appreciate.
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Commented:
Hi,

Firstly you can repair the database with eseutil.

Always verify the database with eseutil /mh. You have dirty shutdown?

If you are not able to recover. You can create new database and move the mailboxes to the new database.

Regards
Valentina

Commented:
In your scenario, first thing I would try is to repair the database using ESEUTIL. Slightly older document, but the process is referenced here - https://blogs.technet.microsoft.com/exchange/2004/06/18/repairing-exchange-databases-with-eseutil-when-and-how/

As you have stated you have no backup of the database, do you have the Exchange transaction logs? This link references the process of playing back log files - http://port25guy.com/2008/11/12/recovering-an-exchange-database-using-log-file-playback/

This will buy you some time to consider your options - https://community.spiceworks.com/how_to/17439-create-a-dialtone-database-in-exchange-2010-and-perform-a-recovery

This is also worth a look for trying to recover the database - https://www.edbmails.com/
AmitIT Architect
Distinguished Expert 2017

Commented:
Do this:

1) First create dial-tone database. That will bring back all your users, without data. https://community.spiceworks.com/how_to/106610-how-to-recover-exchange-2010-database-using-dial-tone-recovery
2) Next you repair the database, using eseutil tool. If you are able to repair. Next create recovery db an extract the data.
3) Merge the data in user mailboxes.
4) If repair fails, you can try out 3rd party edb to pst tool. Like Stellar.
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Author

Commented:
Thanks Valentina Perez & djhath for being so quick to answer.

As I don't trust the disk the files are sitting on, I am in the process of copying what the contents of the exchange DB folder to a different location, at which point I will try the repairs, although for some reason not holding out hope.  This file copy is going to take a number more hours.

I get this error when Exchange  is trying to mount the DB
Source: ESE       Event ID: 481
Information Store (2628) Mailbox Database 2011061718: An attempt to read from the file "E:\Program Files\Microsoft\Exchange Server\V14\Mailbox\Mailbox Database 2011061718\Mailbox Database 2011061718.edb" at offset 0 (0x0000000000000000) for 65536 (0x00010000) bytes failed after 0 seconds with system error 2 (0x00000002): "The system cannot find the file specified. ".  The read operation will fail with error -1811 (0xfffff8ed).  If this error persists then the file may be damaged and may need to be restored from a previous backup.

This repeats a few times with different offsets.


Luckily (I'm calling it well planed) I use Barracuda Email Security (Cloud) which comes with  Email Continuity services, so the users can at least access email while this is under repair.


So based on all that - I will try the eseutil for DB repair once the files have been copied.
But if the repair fails, I am trying to prepared for plan B.
So my previous questions remain;
I know I can great a new DB, clearly that will be blank and have no users in it
1) Can I move the users to the new DB, even if the old DB is not be mounted?
2) Do I need to do anything with outlook on the clients to connect to the new DB?
3) As their mailboxes would be empty in the new DB, will outlook sync the OST file contents back up to exchange?

Thanks for all input, it is greatly appreciated.

Brian

Author

Commented:
So just got this error when trying to copy the contents of  the DB folder to a different disk
"Could not find this item

This is no longer located in E:\Program Files\Microsoft\Exchange Server\V14\Mailbox\Mailbox Database 2011061718.  Verify the item's location and try again"

This error of course is very similar to the error Exchange reported.

I can see the file in the folder using File Explorer, but clearly corrupt, so will not copy.

Looks like creating an empty DB, so the previous questions become important.
Can I move users from a DB that is not mounted.
Do I have to do anything with Outlook to connect to the new DB
Will the OST sync back there contents to the empty DB?

Again any help is appreciated.

Author

Commented:
Thanks Amit for replying.

1) As the users have access to a webmail at present, i don't need to do the dial-tone DB.
2) & 3) looks like the DB is dead - can't even copy it to another location.
4) If I can't copy the DB to a new location, don't think a repair tool will work as it won't be able to be opened.

Thanks for the suggestions.

Brian
Hani M .S. Al-habshiContributor as IT Expert

Commented:
first recover you exchane setting with setup \m:recover command

second you  have no backup so these is no data but use this tool to recover from the users . (recover from old OST/PST users to your new Database  )

https://www.kerneldatarecovery.com/exchange-server-recovery.html

Author

Commented:
Hi Hani - Thank you for your post - I will look at the link.
Commented:
For anyone who comes across this post, this is what I ended up doing.

1st Office, I clearly was not the 1st person who has ended up in this position.
After a lot of searching and reading the basic steps were

Create a New Mail Database
Move the users over to the new Database -> Get-Mailbox –Database “LostDatabaseName” | Set-Mailbox –Database “NewDatabase"
Before you can delete the old DB you need to check and move/delete special roles
      Get-Mailbox -Database <Corrupt DB Name> -Archive
      Get-Mailbox -Database <Corrupt DB Name> -Arbitration (The arbitration mailboxes are the system mailboxes - see links below)
Delete the old Mail Database - via ADSIedit
Run Exchange setup to recreate system mailboxes
As you can only have one public folder DB, need to confirm what "functions" it has and deal with them, i.e. are you actually using the PF as its contents are not replicated down to OST files on the client, therfore you need to do something with the data.
I was lucky that the PF DB was not in use therefore only need to disable OAB distribution via Public Folder
Deleted PF - had to use ADSIedit
Created new PF DB, enable OAB distribution via PF.

That's the server side.

On the client side - I was hoping the OST would connect to the new DB and start to sync up the emails - but as other articles have indicated - it does not work that way.

Opened Outlook on each PC and exported the contents to a PST
In the Control Panel Mail App - deleted ALL Profiles and created a new one to connect to the new DB
Opened Outlook and imported the PST

Articles I used
Move users to new Mail DB
     Spiceworks: https://community.spiceworks.com/topic/247704-move-all-users-to-a-new-empty-exchange-2010-database?utm_source=copy_paste&utm_campaign=growth

Delete Corrupt DB & Recreate System Mailboxes
     https://social.technet.microsoft.com/Forums/en-US/601fbd86-bcc5-466f-8d89-9187753b824b/arbitration-mailboxes-cannot-be-moved-to-another-database-on-the-same-server?forum=exchange2010

Another Article on recreating the system Mailboxes in the new Mail DB
      https://social.technet.microsoft.com/wiki/contents/articles/6874.how-to-recreate-system-mailbox-federatedemail-discoverysearchmailbox-in-exchange-2010.aspx

Change the OAB Distribution Method
      https://www.orionscache.com/2012/08/configuring-the-exchange-2010-offline-address-book/

Note to delete the PF I used ADSIedit as per the previous article - Delete Corrupt DB & Recreate System Mailboxes
     https://social.technet.microsoft.com/Forums/en-US/601fbd86-bcc5-466f-8d89-9187753b824b/arbitration-mailboxes-cannot-be-moved-to-another-database-on-the-same-server?forum=exchange2010
AmitIT Architect
Distinguished Expert 2017

Commented:
Thanks for sharing. However, for large user base, this method would take long time to recover. I advise you to implement dag.

Author

Commented:
Amit

The client only has about 20 users and one server - hard to implement DAG - but I appreciate I never indicated the size I was dealing with.
Time wise ended up being about 15min/user to export, create profile and import email
And about 5 hours to work out what to do on the server.


As for the DB file, it was unreadable - I could not copy it off to another storage device, so was not able to do any repair on it.

I appreciate all help in this matter.  Your responses ensured me there was help out there.

Brian
AmitIT Architect
Distinguished Expert 2017

Commented:
Thanks for the reply Brian. I was just sharing my thoughts, if same method used with large user base. It will take long time to recover. For 20 user, you did the right solution and just keeping regular backup will help you in such situation. Or moving them to office 365 is the best option, as there  you get High availability also.

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