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8TB External USB drive has GPT partitions

Posted: Thu Dec 22, 2022 7:16 am
by ohaya1000
Hi,

I have an 8TB Seagate external drive which I got by removing the drive from a Seagate external drive (the USB connector on the enclosure was flaky).

So I am using that in a dock for now, and I was looking at it in BIU (and you can the partition info in what I provided in this thread: viewtopic.php?t=4204

Anyway, I don't know how/why it happened, but that drive is using GPT and has a small "Microsoft reserved" partition and most of the 8TB is in a second NTFS partition.

I know this is a long shot question, but is there any (safe) way to remove the reserved partition, and make the drive into MBR instead of GPT, and then have the larger partition take the entire drive space?

Like I said, I am also not sure why (and am puzzled about why) it is a GPT drive in the first place, and also why it has that reserved partition. I may have formatted the drive from Windows 10. Would that automatically set the drive up as GPT?

For NTFS and exFat partitions, is there a limitation in size? Is it possible for an 8TB drive to not use GPT and just be MBR and still have large (e.g., taking the entire) drive? Or do such large drives always have to use GPT?

Thanks,
Jim

Re: 8TB External USB drive has GPT partitions

Posted: Thu Dec 22, 2022 7:21 am
by ohaya1000
BTW, the reason I was looking at this drive and partitions in the first place was that I just got a NAS (a Synology DS220j) and was trying to use a package that they have called "USB Copy" and the DS220j kept saying that it couldn't mount the drive, and I've been trying to figure that out. I'm guessing that the problem is that the drive is GPT.

Re: 8TB External USB drive has GPT partitions

Posted: Thu Dec 22, 2022 6:54 pm
by The Seeker
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Re: 8TB External USB drive has GPT partitions

Posted: Thu Dec 22, 2022 9:09 pm
by TeraByte Support
They can if the sector size is >512 bytes.

Re: 8TB External USB drive has GPT partitions

Posted: Thu Dec 22, 2022 11:17 pm
by Brian K
A MBR disk is limited to 2^32 sectors. So if you have 512 byte sectors the maximum disk size is 2^32 * 512 which is 2,199,023,255,552 bytes. That is 2 TiB.

But what if the sectors are larger? Disks with 4K Native sectors, eight times larger than 512 byte sectors, can have a maximum MBR disk size of 16 TiB. They still have 2^32 sectors.