Converting an MBR Disk to GPT


Author
Message
capair45
capair45
Advanced Member
Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)
Group: Forum Members
Posts: 333, Visits: 4.7K
In addition to several other backup storage devices, I have a Western Digital external USB 3.0 HD that receives scheduled images every night. This disk is dedicated to the images, nothing else.

Examining this external HD, it shows it was initialized as an MBR disk. Would there be any advantage to converting this disk to GPT? I have no need to store anything else on this disk. Would my images be affected if I did this?




Windows 10 Home (2004)
Macrium Reflect 7.2.5107
Windows Defender
Malwarebytes Premium 4.2


dbminter
dbminter
Macrium Hero
Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)
Group: Forum Members
Posts: 1.5K, Visits: 16K
The only reason I had to make one of my WD USB HDD's GPT was because of a partition size issue.  It had to be GPT in order to get the necessary partition sizes I needed.  My disk was MBR before I converted it and I had no problems converting it.  It's a simple and quick operation near as I remember it.  I don't see any problems with your images going forward converting an MBR disk to GPT.

capair45
capair45
Advanced Member
Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)
Group: Forum Members
Posts: 333, Visits: 4.7K
dbminter - 11 September 2020 11:34 PM
The only reason I had to make one of my WD USB HDD's GPT was because of a partition size issue.  It had to be GPT in order to get the necessary partition sizes I needed.  My disk was MBR before I converted it and I had no problems converting it.  It's a simple and quick operation near as I remember it.  I don't see any problems with your images going forward converting an MBR disk to GPT.

Your answer is appreciated and most likely I'll leave well enough alone.

Windows 10 Home (2004)
Macrium Reflect 7.2.5107
Windows Defender
Malwarebytes Premium 4.2


dbminter
dbminter
Macrium Hero
Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)Macrium Hero (2.1K reputation)
Group: Forum Members
Posts: 1.5K, Visits: 16K
Probably best.  Unless you really need that disk to be GPT, if MBR is working well enough for you, might as well leave it alone.  I don't know of any advantages to using GPT over MBR.  In fact, I'd never heard of GPT until I had that MBR that needed converting for the larger partition sizes.  Actually, I think it was something about the first partition on the MBR disk couldn't be over a certain size because of some kind of overlapping.  It was limited to specific sector or something in MBR.


So, until you definitely need GPT for whatever reason, you may as well leave it alone as MBR.

jphughan
jphughan
Macrium Evangelist
Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)
Group: Forum Members
Posts: 7.6K, Visits: 54K
From what I remember reading (and sadly I don't remember the nitty gritty details on this one), GPT as a "spec" is much more precisely defined than MBR ever was.  MBR had a lot more variations in its implementation by various vendors in terms of partition IDs and such, so it was more subject to interoperability issues.  And I believe GPT gives it somewhat more resilience to issues, such as having a backup partition table in case the primary location is unreadable, which I don't think MBR has.  Again, I'm a bit hazy here and don't remember any precise details.

Apart from that, MBR only allows 4 primary partitions.  If you want more than 4 partitions, you have to resort to an "extended partition".

And GPT is required for disks larger than 2TB (corrected from original 4TB claim, my mistake).

If you were initializing a new disk, I'd suggest GPT, which Windows now uses as the default these days, because it is a better layout scheme.  (The only exception would be if you were using a flash drive that had to be bootable in Legacy BIOS mode and/or needed the storage device to be readable by Windows XP, in which case you need MBR.)  But for a disk that you've already got set up....on the one hand, the value proposition is minimal unless you need more partitions or more than 4TB.  On the other hand, it's really easy to convert a non-OS disk to GPT....

Edited 13 September 2020 12:37 PM by jphughan
capair45
capair45
Advanced Member
Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)Advanced Member (565 reputation)
Group: Forum Members
Posts: 333, Visits: 4.7K
jphughan - 12 September 2020 4:11 AM
From what I remember reading (and sadly I don't remember the nitty gritty details on this one), GPT as a "spec" is much more precisely defined than MBR ever was.  MBR had a lot more variations in its implementation by various vendors in terms of partition IDs and such, so it was more subject to interoperability issues.  And I believe GPT gives it somewhat more resilience to issues, such as having a backup partition table in case the primary location is unreadable, which I don't think MBR has.  Again, I'm a bit hazy here and don't remember any precise details.

Apart from that, MBR only allows 4 primary partitions.  If you want more than 4 partitions, you have to resort to an "extended partition".

And GPT is required for disks larger than 4TB.

If you were initializing a new disk, I'd suggest GPT, which Windows now uses as the default these days, because it is a better layout scheme.  (The only exception would be if you were using a flash drive that had to be bootable in Legacy BIOS mode and/or needed the storage device to be readable by Windows XP, in which case you need MBR.)  But for a disk that you've already got set up....on the one hand, the value proposition is minimal unless you need more partitions or more than 4TB.  On the other hand, it's really easy to convert a non-OS disk to GPT....

That all makes sense.  I only need one partition and the disk size is less than 4TB.  This was how the disk arrived "out of the box" and I never gave it much thought. 

Windows 10 Home (2004)
Macrium Reflect 7.2.5107
Windows Defender
Malwarebytes Premium 4.2


Danskeman
Danskeman
Proficient Member
Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)Proficient Member (216 reputation)
Group: Forum Members
Posts: 171, Visits: 953
jphughan - 12 September 2020 4:11 AM
From what I remember reading (and sadly I don't remember the nitty gritty details on this one), GPT as a "spec" is much more precisely defined than MBR ever was.  MBR had a lot more variations in its implementation by various vendors in terms of partition IDs and such, so it was more subject to interoperability issues.  And I believe GPT gives it somewhat more resilience to issues, such as having a backup partition table in case the primary location is unreadable, which I don't think MBR has.  Again, I'm a bit hazy here and don't remember any precise details.

Apart from that, MBR only allows 4 primary partitions.  If you want more than 4 partitions, you have to resort to an "extended partition".

And GPT is required for disks larger than 4TB.

If you were initializing a new disk, I'd suggest GPT, which Windows now uses as the default these days, because it is a better layout scheme.  (The only exception would be if you were using a flash drive that had to be bootable in Legacy BIOS mode and/or needed the storage device to be readable by Windows XP, in which case you need MBR.)  But for a disk that you've already got set up....on the one hand, the value proposition is minimal unless you need more partitions or more than 4TB.  On the other hand, it's really easy to convert a non-OS disk to GPT....

​GPT is required for drives over 2 TiB (approx. 2.2 TB).
jphughan
jphughan
Macrium Evangelist
Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)
Group: Forum Members
Posts: 7.6K, Visits: 54K
Bah, my mistake. Edited my previous post. Thanks!
zgrayfox
zgrayfox
New Member
New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)New Member (9 reputation)
Group: Forum Members
Posts: 7, Visits: 2K

Just a minor clarification - all these maximums assume that the disk has 512 byte sectors - disks can present a sector size other than 512 bytes, such as some USB external drives. A sector size of 4096 results in an eight-fold increase in the size of a partition that can be defined using MBR, allowing partitions up to 16 TiB (232 × 4096 bytes) in size.  An example of a 5 TB MBR disk/partition.





jphughan
jphughan
Macrium Evangelist
Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)Macrium Evangelist (11K reputation)
Group: Forum Members
Posts: 7.6K, Visits: 54K
^ Agreed, and the downside of the hack implemented by some such enclosures is that drives initialized in that enclosure are unreadable elsewhere, and vice versa. I had one of those enclosures and didn’t realize it until I installed a 4TB disk that I had initialized elsewhere into it, since it only activated that hack with >2TB disks. When I figured out what it was doing, it went straight to the trash. Setting up a disk that can only be read by that device or another one that implements an ugly hack is unacceptable in my view.

There are still very few disks that actually present as 4K, so-called “4Kn disks”. Most disks with 4K physical sectors still present as having 512-byte sectors, called “512e”. And I suspect relatively few people are using 4Kn disks in contexts that require MBR. And thankfully, the demise of Windows XP means that those nasty enclosures are going away too.
Edited 13 September 2020 4:01 PM by jphughan
GO

Merge Selected

Merge into selected topic...



Merge into merge target...



Merge into a specific topic ID...




Reading This Topic

Login

Explore
Messages
Mentions
Search