3Tb HDD on an XP32 box?

I suspect that what you're running into is the 2.2-terabyte limit in the standard PC Master Boot Record. This would correspond to 32 bits worth of sectors (4 hexabillion) at 512 bytes each.

Probably, when your partition table is being built, the software you're using is trying to read the hard drive size via the PC BIOS, and the sector count is wrapping around past 4 billion. The program ends up with (3 terabytes - 2.2 terabytes) worth of sectors, and so you only get 750 GB.

I'm not an expert in the PC BIOS, but I suspect that the "read drive sector count" call returns a 32-bit result, and the BIOS isn't smart enough to clip (rather than wrap) at 2.2 terabytes. If that's the case, no matter what program you use, you'll hit the same behavior.

There's probably a fix, although it won't be trivial. What you would need to do is let the software partition the drive. If you want more than one partition, delete the single 750-gig existing one and create the smaller ones you want at first, and then create a final partition which uses up the remainder of the 750 GB space.

Then go in with a sector-level disk editing program, and edit the partition table by hand. Take a look at

You'd want to edit the "number of sectors in partition" value at offset 12 (0x0C) for the last (or only) partition and set it to "0xFFFFFFFF" (or slightly less than that) and store this entry. This would expand that partition to 2.2 terabytes.

Save the MBR, reboot, and I think you'd find that you have more space available.

HOWEVER: depending on how your PC accesses the drive, you could find that Bad Things happen when it tries to write beyond the 2.2-terabyte boundary - reads and writes might wrap around to the beginning of the disk. For that reason, it would probably be safest to limit the total size of the partitions you create to slightly less than 2.2 terabytes, so that all of the subsequent I/O operations are compatible with a

Pretty sure something nasty would happen if I tried for more than 2.2Gb partition - but I can't even get that.

I was thinking more along the lines of 2x 1.5Tb partitions.

That _may_ be workable, but you're probably going to have to do more math, and become more familiar with the PC Master Boot Record and how to hack it.

Setting up the MBR to work in LBA (logical block address) mode, rather than C/H/S, would probably make things easier.

Again, it's going to depend a lot on your PC and its device drivers. If it's capable of accessing the drive in LBA48 mode (with a 48-bit logical block address) you may get away with it. If not, you may be stuck with 2.2 terabytes at most.

This is the wrong group for a start.

Either use a 2TB drive with MBR partition table (that XP does support), or upgrade to a later version of Windows (7 onwards supports GPT).

der

If you can live with it as non bootable data only, put it in a USB3 enclosu re and use it that way. XP is fine with 3tb USB drives.

Someone gave me one of those they'd dropped on the USB connector - figuring out where all the ripped up tracks went became a "back burner" project.

Which would you reccomend?

I just got a couple of the Plugable ones (2.5/3.5 inch) and they work great--it really cut down my backup/restore times. I built myself a new Qubes box (Thinkpad T430, 16G, 1T SSD) which required restoring all my VMs from backup. (I could have used dd and then resized the partition and file system, but that's a pain on an encrypted partition.)

Cheers

Phil Hobbs

uk.comp.homebuilt

-- (\_/) (='.'=) "Between two evils, I always pick (")_(") the one I never tried before." - Mae West