Meaning of Warning: number of bytes per sector mismatches

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JamesH
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Joined: 22 Jul 2014, 22:43

Meaning of Warning: number of bytes per sector mismatches

#1 Post by JamesH » 22 Jul 2014, 22:49

I've looked in the Wiki, searched these forums and done a Google search. I can't find a definitive answer for what "Warning: number of bytes per sector mismatches" means. Its probably important and I'm sure knowing this would help out a lot of people so hopefully we can get a definitive explanation of it here.

I got this while analyzing the partitions on a disk, below is the output. Could someone please explain the relevance of this warning and what its trying to convey. I'm not even sure by the phasing what 2048 vs 512 means. Is the partition table saying 512 and NTFS structures saying 2048? Really have no clue but probably very much need to understand this.

Thanks in advance.


TestDisk 7.0-WIP, Data Recovery Utility, June 2014
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org

Disk /dev/sdd - 6000 GB / 5588 GiB - CHS 729576 255 63
Current partition structure:
Partition Start End Size in sectors

Warning: number of bytes per sector mismatches 2048 (NTFS) != 512 (HD)
1 P MS Data 2048 206847 204800
Warning: number of bytes per sector mismatches 2048 (NTFS) != 512 (HD)
2 P MS Data 206848 126035967 125829120

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JamesH
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Joined: 22 Jul 2014, 22:43

Re: Meaning of Warning: number of bytes per sector mismatche

#2 Post by JamesH » 24 Jul 2014, 19:01

Anyone? When Googling this I've seen it mentioned quite a few times in other people's logs and questions, but I have yet to come across any explanation of what it actually means. Do the TestDisk programmers read these forums?

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cgrenier
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Re: Meaning of Warning: number of bytes per sector mismatche

#3 Post by cgrenier » 24 Jul 2014, 21:26

The boot sector of each NTFS partition contains the information that the disk sector size is 2048 bytes.
The Operating System returns a sector size of 512 bytes for this disk.

JamesH
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Joined: 22 Jul 2014, 22:43

Re: Meaning of Warning: number of bytes per sector mismatche

#4 Post by JamesH » 25 Jul 2014, 01:42

So the left info is always the reported file system sector size and the right the OS sector size. Very good to know that for sure.

Now a matter of figuring out which was actually correct...

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cgrenier
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Re: Meaning of Warning: number of bytes per sector mismatche

#5 Post by cgrenier » 27 Jul 2014, 19:13

Sector size is usually 512 and sometimes 4096 for recent disk of big capacity.
I have never seen 2048 bytes per sector myself except for CD.

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