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gpt disks

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richw1234

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Mar 4, 2004
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Hi there, does anyone know whether it is possible to add extra drive space to a partition which has been created using GPT disks in Windows 2003 SP1. Basically, we are looking at a 2TB GPT partition, we would then want to increase this to 4TB at a later date, is this possible or do we have to kill the partition off and re-create it using the additional space?
 
As per MS;

How big can a GPT disk be?
In theory, a GPT disk can be up to 2^64 logical blocks in length. Logical blocks are commonly 512 bytes in size.

The maximum partition (and disk) size is a function of the operating system version. Windows XP and the original release of Windows Server 2003 have a limit of 2TB per physical disk, including all partitions. For Windows Server 2003 SP1 Windows XP x64 edition, and later versions, the maximum raw partition of 18 exabytes can be supported. (Windows file systems currently are limited to 256 terabytes each.)

How many partitions can a GPT disk have?
The specification allows an almost unlimited number of partitions, but the Windows implementation restricts this to 128 partitions. The number of partitions is limited by the amount of space reserved for partition entries in the GPT.
 
OK, thanks but it did not answer my question :(

Perhaps I wasn't clear enough, If a GPT partition is already in place but is running out of drive space, can another GPT disk be glued to the existing disk to give it more drive space? Scalability is the word here!!
 
Besides the architectural aspect, I am assuming the same principles apply in terms of setting up volumes. Although you are limited to 2TB per physical disk, it doesn't mean you can't tack on another 2TB disk for instance. GPT disks can be either basic or dynamic in nature, therefore if dynamic you can create spanned volumes which can extend.
See the faq for more details

Hope this helps.
 
Do you know if there is any performance issues with the more partitions used?
 
To answer your question, yes, you can add onto your gpt partition (and you are limited to 2TB so long as you SP1 installed), however, I have never done this, but I also have a 2TB gpt partition on a raid 5 and I'm going to experiment and add another hd soon to see how it goes (I always cringe when expanding a partition table, however, due to GPT's redundancy it would seem safer to do it on this table than others...maybe).

As for performance of multiple partitions, I'm not too sure. Since you're talking about 2TB, I'm sure you have some type of array going on so there would be a number of factors to involve other than simply the # of partitions. I would also say it depends on what you're using your array for and the types of files and sizes of these files.

Nate
 
oops, forgot to type the word "not," it should you (and you are NOT limited to 2TB so long as you have SP1 installed). Sorry about that.
 
Rich,
I just thought you might want to know that I have a 4 disk 750gb raid 5 array and I'm migrating another 750gb to the array right now and that process is going to take a total of about 72 hours! So when you plan your 2 TB -> 4TB upgrade you should definitely allocate a lot of time (the array is still up of course during the migration). I'm using 3ware's new 16 port sata card (9650 I think)in a new server. I still have not decided what software/utility I'm going to use to expand the partition table in 2k3.

Nate
 
Thanks for the info, please let me know how you get on.
 
After the merge completed (I used the 3ware web utility, which takes 30-50% longer, but you can use your server still while it's migrating) that took 72 hours it was extremely easy to expand the partition table for the volume.

I rebooted in safe mode with command prompt, at command prompt I used the diskpart command and this was what I needed to type

diskpart
list volume
select volume 0 (or whatever volume # is yours)
extend (took 5-10 seconds for me)
list volume (took 5 seconds to list, but seemed like forever, and the additional storage on that volume was shown instantly)
exit

ctrl+alt+del to restart. Open up My Computer and the extra space should be shown. I'm doing a verify on the unit now to make sure everything is fine, but the part I was fearing the most was actually extremely easy and took virtually no time (especially since the migration took days!).

I could not find (at this time) any software that supported the expansion/merge of GPT partitions. If someone knows of one, please let me know, but since the command utility is so easy and quick it seems like the best option to me (but perhaps not for everyone).

Hope this helps!

Nate
 
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