Discussion:
Problem with GPT partition disk, moving from SATA-to-USB caddy to SATA
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NY
2017-08-09 11:24:49 UTC
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I've just got a new 4 TB hard drive to use for all my data (photos, videos
etc).

I initially connected it to my Windows 7 PC via a SATA-to-USB caddy
interface so I could transfer data from another disk (connected by SATA
inside the PC).

The drive didn't show up in Windows Explorer so I went into Computer
Management | Disk Manager and it wanted me to initialise the disk, and to
choose either MBR or GPT. I chose GPT as being the newer partition type and
one that could see the whole 4 TB as a single partition. I then needed to
format it as NTFS. No problem.

Having copied all the data from the 1 TB that I was going to remove, I
removed the 1 TB and put the 4 TB in its place, now conencted to a SATA port
within the PC.

But the partition didn't show in Windows Explorer and I needed to initialise
the disk all over again - and copy the data again :-(


Is there anything about GPT which means that a disk must always be connected
to the PC by the same interface, or should it be possible to initialise and
format the disk while it's connected by the caddy, copy data on and then
still see the partitions, filesystem and data when I connect the disk
directly to the PC's SATA? That works for all other drives, but then maybe
they are all the older MBR partition.
Paul
2017-08-09 13:42:48 UTC
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Post by NY
I've just got a new 4 TB hard drive to use for all my data (photos,
videos etc).
I initially connected it to my Windows 7 PC via a SATA-to-USB caddy
interface so I could transfer data from another disk (connected by SATA
inside the PC).
The drive didn't show up in Windows Explorer so I went into Computer
Management | Disk Manager and it wanted me to initialise the disk, and
to choose either MBR or GPT. I chose GPT as being the newer partition
type and one that could see the whole 4 TB as a single partition. I then
needed to format it as NTFS. No problem.
Having copied all the data from the 1 TB that I was going to remove, I
removed the 1 TB and put the 4 TB in its place, now conencted to a SATA
port within the PC.
But the partition didn't show in Windows Explorer and I needed to
initialise the disk all over again - and copy the data again :-(
Is there anything about GPT which means that a disk must always be
connected to the PC by the same interface, or should it be possible to
initialise and format the disk while it's connected by the caddy, copy
data on and then still see the partitions, filesystem and data when I
connect the disk directly to the PC's SATA? That works for all other
drives, but then maybe they are all the older MBR partition.
It could be that the USB to SATA device has a capacity limit.

And, just maybe, the OS can't "see" the end of the drive.

Check the USB to SATA device web site, and see if there is
a spec for capacity.

Paul
NY
2017-08-09 14:18:07 UTC
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Post by Paul
It could be that the USB to SATA device has a capacity limit.
And, just maybe, the OS can't "see" the end of the drive.
Check the USB to SATA device web site, and see if there is
a spec for capacity.
Unfortunately the adaptor was one I took from a 2 TB external drive where
the drive itself had failed, so it's not a branded adaptor that I can look
up on the web. Maybe being a cheapskate and using what I have lying around
has come back to bite me on the bum :-(

I'm surprised that the PC was able to see what appeared to be the whole
drive and create a whole-disk partition, if there was a problem with the
adaptor.

I hope it's not a problem with the drive or the motherboard SATA controller,
because it's a lot of work to populate the drive again (from backups) if I
ever lose access to the data again...

I suppose if I'd thought it through, I'd have connected the "source" drive
to another m/b SATA (eg the one for the DVD drive) which would have probably
allowed me to copy more quickly that with the source drive on the SATA-USB
adaptor. But it's part-way through now.
Paul
2017-08-09 14:47:59 UTC
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Post by NY
Post by Paul
It could be that the USB to SATA device has a capacity limit.
And, just maybe, the OS can't "see" the end of the drive.
Check the USB to SATA device web site, and see if there is
a spec for capacity.
Unfortunately the adaptor was one I took from a 2 TB external drive
where the drive itself had failed, so it's not a branded adaptor that I
can look up on the web. Maybe being a cheapskate and using what I have
lying around has come back to bite me on the bum :-(
I'm surprised that the PC was able to see what appeared to be the whole
drive and create a whole-disk partition, if there was a problem with the
adaptor.
I hope it's not a problem with the drive or the motherboard SATA
controller, because it's a lot of work to populate the drive again (from
backups) if I ever lose access to the data again...
I suppose if I'd thought it through, I'd have connected the "source"
drive to another m/b SATA (eg the one for the DVD drive) which would
have probably allowed me to copy more quickly that with the source drive
on the SATA-USB adaptor. But it's part-way through now.
When you shop for another adapter, they come in two flavors.

Even though the product may say "USB3", some have a SATA II chip
and some have a SATA III chip. You want the latter one (1053E).
The letter on the end, may indicate the "better" one. If you
see a "particularly cheap" adapter, still nice looking, in the
store, that will have the SATA II chip in it.

The enclosure should support UASP (SCSI protocol).

With all ducks lined up, you could get close to 500MB
per second from your new enclosure (assumes native USB3
sourced by the Southbridge). And if you insert an SSD
into the enclosure, it's going to run pretty close
to its hardware limits.

I don't think mine is quite that good, but mine goes up
to (at least) 4TB as stated on the box, and it does a bit
more than 200MB/sec. Which is fine for most hard drives.
The very best hard drive you can buy today, is a 15K drive
that does 300MB/sec, so my enclosure would "hold that
one back". But the chances of me owning such a hard
drive, are zero :-)

My enclosures were an impulse buy, while I was in the
computer store, so I didn't do any "research" first.
I think the enclosure was $30 or so, and comes with a
wall adapter (+12V).

When I visited the web site of the manufacturer today,
the capacity of that enclosure is listed as "8TB". So
I guess they're still figuring out whether it has a
limit or not.

And I can't say for sure, whether GPT over USB is an
issue or not. I don't think it is, but then again,
I haven't tested every possible permutation here either.
I run my adapters with the enclosure off them, and
it isn't very convenient to set them up as a result.

Paul
Tim Slattery
2017-08-09 14:49:37 UTC
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Post by NY
I've just got a new 4 TB hard drive to use for all my data (photos, videos
etc).
I initially connected it to my Windows 7 PC via a SATA-to-USB caddy
interface so I could transfer data from another disk (connected by SATA
inside the PC).
The drive didn't show up in Windows Explorer so I went into Computer
Management | Disk Manager and it wanted me to initialise the disk, and to
choose either MBR or GPT. I chose GPT as being the newer partition type and
one that could see the whole 4 TB as a single partition. I then needed to
format it as NTFS. No problem.
One note here: the MBR partition table cannot handle a disk larger
than 2TB. If you use MBR on a larger disk, you won't be able to use
more than 2TB of it, regardless of your partitioning scheme.
--
Tim Slattery
tim <at> risingdove <dot> com
Paul
2017-08-09 15:02:11 UTC
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Post by Tim Slattery
Post by NY
I've just got a new 4 TB hard drive to use for all my data (photos, videos
etc).
I initially connected it to my Windows 7 PC via a SATA-to-USB caddy
interface so I could transfer data from another disk (connected by SATA
inside the PC).
The drive didn't show up in Windows Explorer so I went into Computer
Management | Disk Manager and it wanted me to initialise the disk, and to
choose either MBR or GPT. I chose GPT as being the newer partition type and
one that could see the whole 4 TB as a single partition. I then needed to
format it as NTFS. No problem.
One note here: the MBR partition table cannot handle a disk larger
than 2TB. If you use MBR on a larger disk, you won't be able to use
more than 2TB of it, regardless of your partitioning scheme.
He's using GPT though.

If you examine the MBR in that case, it will show
a (bogus) single partition of type 0xEE, and the
capacity listed will be quite large. This practice
on GPT disks, is referred to as a "protective MBR",
the contents of which are intended to prevent
MBR OSes from messing with the disk. An MBR OS
would conclude "the disk is full" when it sees
the particulars of that 0xEE partition.

Paul
Char Jackson
2017-08-09 16:41:37 UTC
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Post by NY
I've just got a new 4 TB hard drive to use for all my data (photos, videos
etc).
I initially connected it to my Windows 7 PC via a SATA-to-USB caddy
interface so I could transfer data from another disk (connected by SATA
inside the PC).
The drive didn't show up in Windows Explorer so I went into Computer
Management | Disk Manager and it wanted me to initialise the disk, and to
choose either MBR or GPT. I chose GPT as being the newer partition type and
one that could see the whole 4 TB as a single partition. I then needed to
format it as NTFS. No problem.
Having copied all the data from the 1 TB that I was going to remove, I
removed the 1 TB and put the 4 TB in its place, now conencted to a SATA port
within the PC.
But the partition didn't show in Windows Explorer and I needed to initialise
the disk all over again - and copy the data again :-(
Is there anything about GPT which means that a disk must always be connected
to the PC by the same interface, or should it be possible to initialise and
format the disk while it's connected by the caddy, copy data on and then
still see the partitions, filesystem and data when I connect the disk
directly to the PC's SATA? That works for all other drives, but then maybe
they are all the older MBR partition.
I'm thinking it's a quirk of your USB-SATA adapter.

Awhile back, I bought a 4TB external drive where the actual drive was
SATA but the case interface was USB. Naturally, everything just worked,
but my reason for buying it was to harvest the drive out of it since I
don't use external drives here. When I harvested the drive and plugged
it into an internal SATA port, I was surprised to see that it had two
partitions of 2TB each. The electronics in the external case had joined
the two partitions and presented them to the PC as a single 4TB
partition.

That's probably not your issue, but it illustrates my point that a USB
adapter can show the PC one thing, while connecting that same drive to
an internal SATA port can show the PC something quite different. If your
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.

I know you've moved well past the point now, so this is just my take on
what might have happened. 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.
--
Char Jackson
Mike Tomlinson
2017-08-10 06:57:50 UTC
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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
If your
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
+1
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
+1
--
(\_/)
(='.'=) "Between two evils, I always pick
(")_(") the one I never tried before." - Mae West
Paul
2017-08-10 12:28:22 UTC
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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
If your
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
+1
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
+1
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"

https://web.archive.org/web/20041024150852if_/http://www.t10.org:80/t13/technical/e00101r6.pdf

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.

https://mh-nexus.de/en/hxd/

Paul
NY
2017-08-10 16:26:49 UTC
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Post by Char Jackson
If your
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
Yes, if I'd known that the external adaptor would have a problem addressing
the 4 TB drive, I'd do what I did second time round: shut down PC to remove
old 1 TB drive, put 4 TB in its place, reboot and connect 1 TB to external
adaptor and copy everything.
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
Yes, I'll get a decent adaptor for future use, just in case I ever need to
transfer anything to/from a larger disk again. What are the key spec that I
should look out for in any transfer device. I see that Anker do one:
https://www.amazon.co.uk/d/Cables/Anker-Converter-Adapter-Cable-included/B006J2L0ZM/ref=sr_1_1?ie=UTF8&qid=1502381906&sr=8-1&keywords=anker+sata+usb

It's my own fault for trying to do it on the cheap. Rather than buy a
dedicated adaptor, I cannibalised the dead external HDD when the drive
failed and thought "ah, goody, a SATA-to-USB adaptor". I've used it loads of
times, but never with a drive as big as 4 TB - usually it's been under 1 TB.

Once i'm really sure that the 4 TB is working OK, I can start to delete
things off the C drive that I've copied to the 4 TB. It's all backed up on
other drives, but it would still be a time-consuming hassle if I needed to
copy it onto the online drive all over again!

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