SATA to USB cable sector size

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I have been having a lot of problems connecting different kinds of SATA drives to my PCs using SATA to USB adapters and the problems seem to boil down to sector size mismatches: sometimes the original sector size is 512 but the adapter "presents" a sector size of 4096, thus rendering the contents of the drive illegible to the OS, or vice versa, showing 512 instead of 4096 with the same results. I recall looking into this a couple years ago and found out the problem is in the adapters themselves, because of a "thing" related to the SATA version or SATA mode supported by the adapters, however I don't seem to find much information about this these days. What exactly is this "thing" I'm looking for when buying an adapter, so I know it won't mess with my drives?

These are the most relevant places and questions I've looked up so far, but don't exactly address what is the "thing" that's missing:

TL;DR

There is something regarding the SATA version or some SATA mode that makes some adapters mess up sector sizes on some drives, making the illegible but not unusable, i.e.: I can create a new partition table and use them just fine, except the next adapter I try may or may not force me to do the same. What is it?

Best Answer

What exactly is this "thing" I'm looking for when buying an adapter, so I know it won't mess with my drives?

As it's stated in this answer:

The enclosure exposes the drive to the computer as an Advanced Format 4Kn device, allowing the use of MBR for compatibility with Windows XP systems.

(which this blog post further expands):

Advanced Format was adopted by drive manufacturers to increase the size of a physical sector on the drive from 512 bytes to 4 kiB (i.e. 8 times larger).

the problem lies in a feature that's known as Advanced Format, that translates 512 bytes per physical sector into 4096 ones to improve efficiency; which some adapter manufacturers don't implement in their hardware, resulting in the wrong sector sizes being exposed to the OS.

And as to how to look for that feature in an adapter: You just have to know how to identify the drives' and adapters' capabilities and maybe have one or two lying around just in case.

Related Solutions

Determine Sector Size on External Hard Drive – How To

Run wmic partition get BlockSize, StartingOffset, Name, Index from a Windows Command Prompt. The output looks like:

BlockSize  Index  Name                   StartingOffset
512        0      Disk #0, Partition #0  1048576
512        1      Disk #0, Partition #1  105906176
512        0      Disk #1, Partition #0  32256

Where block size is the drive's sector size. It unfortunately doesn't list the drive letter.

Also as I understand the article, the drive will still list that it has 512 byte sectors even though internally it uses 4kb sectors. So the only way may be to get the drive's spec sheet.

Linux – Logical Sector Size Changes with USB vs SATA

It's a little late, but I had a similar problem after the USB port of my IOMEGA hard disk case broke off. I switched to another USB-2-SATA case just to discover, that I could not mount the EXT4 partition. For some reason the IOMEGA case reported the logical sector size to be 4096, but my new case said it was only 512 bytes. This screws up the MS-DOS partitioning table.

It was driving me nuts, because with the help of testdisk I was able to access the partition, when changing the sector size, but I found no way to change the sector size system-wide. It turns out, that's not necessary, because EXT4 does not care for sector size, you just have to find the beginning of the partition you'd like to access.

Quick fix: Use a loopback device to shift to the correct position of the partition.

Permanent fix: Rewrite partition table, accordingly.

In my case the affected drive was /dev/sdb.

My quick fix was relatively easy, since I had only one partition beginning at sector 63.

$ sudo sfdisk -d /dev/sdb
# partition table of /dev/sdb
unit: sectors

/dev/sdb1 : start=       63, size=623708785, Id=83

Now we have to calculate the partition's position, when sector size still was 4096 bytes:

63 sectors * 4096 bytes = 258048 bytes

And use that with losetup:

$ sudo losetup /dev/loop0 /dev/sdb -o 258048
$ sudo mount /dev/loop0 /mnt

Your partition should now be mounted at /mnt.

For the longterm fix I used sfdisk to dump the partition layout:

$ sudo sfdisk -d /dev/sdb > sdb.partitions.sfdisk.text

Fixing the partition table by multiplying with the beginning sector with 8 where appropriate -- here I realized my partition table was kinda screwed from the beginning.

I edited the partition table dump with nano sdb.partitions.sfdisk.text:

/dev/sdb1 : start=       63, size=623708785, Id=83

to:

/dev/sdb1 : start=      504, size=623708785, Id=83

and later on extended the partition to use all available space (which I determined by other means):

/dev/sdb1 : start=      504, size=625141944, Id=83

Last step is to write back the partition table with:

$ sudo sh -c 'cat sdb.partitions.sfdisk.text | sfdisk /dev/sdb'

Best Answer

Related Solutions

Determine Sector Size on External Hard Drive – How To

Linux – Logical Sector Size Changes with USB vs SATA

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