Convert to GPT from MBR without losing any data (work on Exchange DAG)

Hi,
Recently my exchange server 2016 DAG was running out of space, my database reaches 2 TB and the MBR cannot be extended anymore, so I need to convert to GPT. I tried Diskpart, which is a good builtin tool using the following command, but it fails and returns the following error

Virtual Disk Service error:
The specified disk is not convertible. CDROMs and DVDs
are examples of disks that are not convertable.

Based on some googling and reading it seems that this command will work fine if I clear the disk (format it) which cause a full data lost on the disk, and this is not applicable on my case, I have 2 exchange server 2016 with 2TB of data on one of the disk, resyncing the data will take several days.

The Fix
I find this super tools
https://sourceforge.net/projects/gptgen/files/gptgen/v1.1/gptgen-1.1.zip/download
Just download it and place it on drive C: or whatever drive other than you want to convert and run the following command gptgen.exe, the output will be

where device_path is the full path to the device file,
e.g.\\.\physicaldrive0.

Available arguments (no "-wm"-style argument combining support):
-b , --backup : write a backup of the original MBR to
-c nnn, --count nnn: build a GPT containing nnn entries (default=128)
-h, --help, --usage: display this help message
-k, --keep-going: don't ask user if a boot partition is found
-m, --keepmbr: keep the existing MBR, don't write a protective MBR
-w, --write: write directly to the disk, not to separate files

One of the required parameters is the disk number and we can get it from Diskpart, using the following command
> Diskpart
>> List disk


You need to know the disk number you want to convert. Let's assume that the disk you want to convert is disk 1, just remember the number, now exit Diskpart and navigate to GPTGen and execute the following command
gptgen.exe -w \\.\physicaldrive1

The -w parameter is used to write GPT table and is required in the converting process, just make sure to write the correct disk number, in my case, it's 1.
The output will be similar to


That easy, GPT without losing any data
No need to reboot, even though I recommend to reboot and make sure that everything is working fine. Also, I recommend before doing, try to minimize IO on the disk, place the server in maintenance mode, turn the services off, and also backup your data if you can. Gptgen have the option to backup the current MBR before converting it.

Enjoy :D

Exchange 2010 / 2013 Server Single Instance Storage.... is gone

Exchange Single Instance Storage (SIS)

What is SIS

SIS creates a single instance of messages sent to multiple recipients within the same database. Simply said, the first one gets a copy of the message in his or her mailbox, others get a referral to the message.

Why it was used?

In old days where Storage were really limited, most of the mailboxes reside on a single database, and even the Disk Disk performance was not that good and the good performance disk was really expansive, so SIS saved a lot of Disk IO and space.

So what is the benefit:

This Really save a lot of space and Disk IO on the database.
Exchange SIS was used on all version of Exchange from the beginning till Exchange 2007, In exchange 2007 SIS will only be enabled to the attachments only, which wont offer much regarding for performance or disk space saving.

Why its being removed?

Starting the disk price are getting low and storage now are cheap.
Users mailboxes are distributed between several database.
Microsoft had enhanced ESE performance more than all other previous version of Exchange, so SIS will not be the performance saving anymore.
Microsoft ESE now compress the message Body and header by default which will be a better saving.

What about Attachments, are they compress too?

The answer is NO, There is no need to compress the attachment for:
1- compressing and decompressing will be CPU intensive
2- Most of the attachments are already in compressed state (Zip - PDF - Docx - JPG)

Is compression the answer to replacing single instancing all together?

The answer to that question is that it really does depend. There are certain scenarios where SIS may be viable:

Environments that only send Rich-Text Format messages. The compression algorithms in Exchange 2010 do not compress RTF message blobs because they already exist in their most compressible form.
Sending large attachments to many users. For example, sending a large (30 MB+) attachment to 20 users. Even if there were only 5 recipients out of the 20 on the same database, in Exchange 2003 that meant the 30MB attachment was stored once instead of 5 times on that database. In Exchange 2010, that attachment is stored 5 times (150 MB for that database) and isn’t compressed. But depending on your storage architecture, the capacity to handle this should be there. Also, your email retention requirements will help here, by forcing the removal of the data after a certain period of time.
Business or organizational archives that are used to maintain immutable copies of messaging data benefit from single instancing because the system only has to keep one copy of the data, which is useful when you need to maintain that data indefinitely for compliance purposes.

Community thinks?

- Even if disk are cheap, we still need to take care of it insted of wasting the space for having several copy of the email !

Yes, sure but content compression should offer a good disk saving.
- And what about attachment?
Simply if you really have it as an issue, you will need use Sharepoint or third party email attachment management.

- What is the Compression MS used
- From Here
- Wikipedia

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