Post by Mike Tomlinson Post by Char Jackson
I'm thinking it's a quirk of your USB-SATA adapter.
Agreed. OP stated he took it from a failed 2TB external drive. it's
likely it only supports 48-bit LBA, which would limit it to 2TB. Any
writes past that would 'wrap around' to the beginning of the disk,
blatting the MBR and partition table and making it look like a virgin,
uninitialised disk - which is what happened when he plugged it into a
motherboard port of his system.
Post by Char Jackson
long term goal is to connect the drive to an internal SATA port, I would
just do that as a first step and everything should be fine
Post by Char Jackson
When you ask if there's something strange
about GPT, I'd say no, it's more likely just your USB adapter getting in
the way and doing its own thing
The limit on my Firewire to IDE box. This is "non-48bit" LBA
or 28 bit LBA.
2^28 * 512 = 2^37 = 137,438,953,472 "137GB"
On MBR partitioned disks, the partition slots have room for
32 bit LBA (sector) values. This limits how big a partition
that can be declared. It's not a limiting value for the
actual physical transfer mechanism.
2^32 * 512 = 2^41 = 2,199,023,255,552 "2.2TB"
Around ATA/ATAPI ver 6 or so, 48 bit LBA was invented. It
uses double pumped registers to extend the address format.
2^48 * 512 = 2^57 = 144,115,188,075,855,872 "+inf"
Other inadvertent limits, I've seen no hints as to where
they're coming from. The first one is real, because I fought
with that (and lost) on my Firewire box. The second requires
GPT to fix (and the associated support that goes with it).
SATA always had 48-bit LBA, to the best of my knowledge. It
was introduced after the 48-bit LBA era (year 2003 ?).
In the above, a sector size of 512 bytes was used to do the
math. But other values are possible - it's the OS and the
hardware which might not handle them. There are native 4096
byte disks on the market now - no backup tools can handle
munging between 512 byte and 4096N disks, and you have
the usual OS limitations. If you buy one of those (so-called)
Enterprise disks, it's about as useful as a new boat anchor.
The kind consumers use are 512e (512 emulated outside,
4096 physical inside), and those are compatible if only
slightly inconvenient (could use alignment to aid
performance in WinXP).
When other limit values come out, I don't have any
ideas as to where the limits come from.
And even testing what is going on, could be time consuming,
if you don't understand what it does under failure conditions.
If you have a good model for what the failure is, the "search"
for it (binary search) might only take a few seconds.
If you want to "paddle around" in your disk drive, there
is always this. I don't know if I've had occasion to walk
out to the end of my 4TB drives, with this program yet, so
I don't know what limits this might have. On WinXP, the OS
would probably interfere with going past 2.2TB. There is a
separate menu item, for raw disk access. And you can do the
access "read-only", if you're a butter-fingers or something.
And when doing searches, if your disk goes fast enough,
this can search at around 600MB/sec.