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If I GPT partition a 4TB disk when it is connected to SATA, then it works fine. If I take the disk and put in the an USB3 enclosure, then I get

[root@localhost liveuser]# sfdisk /dev/sdb 
sfdisk: Checking that no-one is using this disk right now ...
sfdisk: OK

Disk /dev/sdb: 486401 cylinders, 255 heads, 63 sectors/track
Old situation:
Units: cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1          0+ 267349- 267350- 2147483647+  ee  GPT
                start: (c,h,s) expected (0,0,2) found (0,0,1)
/dev/sdb2          0       -       0          0    0  Empty
/dev/sdb3          0       -       0          0    0  Empty
/dev/sdb4          0       -       0          0    0  Empty
sfdisk: Input in the following format; absent fields get a default value.
<start> <size> <type [E,S,L,X,hex]> <bootable [-,*]> <c,h,s> <c,h,s>
Usually you only need to specify <start> and <size> (and perhaps <type>).

sfdisk: /dev/sdb1 :

There is an EXT3 filesystem on this disk.

Question

Why can't a GPT partitioned disk on SATA be read on USB?

Jasmine Lognnes
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1 Answers1

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Most likely in one of the cases (either sata or usb) it is using its native 4K sectors, and in the other mode it is emulating 512B sectors.

There may be bios/sata controller options that help fix that. Or you can format it attached by USB if that is the intended use. There might even be a jumper on the drive to force it to always emulate 512B sectors.

Grant
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