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Why does windows insist on always putting the first partition at sector 2048 on a HDD? Between the MBR and that is just wasted space full of zeros.

Is there some special reason for that? Yea its only 1MB but still... the space can't be made use of so it is wasted.

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You sure the drive isn't GPT instead of MBR? –  Breakthrough Sep 16 '11 at 11:23
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closed as not constructive by Linker3000, random Sep 17 '11 at 1:48

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2 Answers

up vote 3 down vote accepted

It's for sector-alignment on the newer Advanced Format drives with 4K sectors, and for the future. It's apparently mentioned in a now-withdrawn Microsoft Knowledge Base article, captured and quoted on Wikipedia:

In earlier versions of Windows, the default starting offset for the first partition on a hard disk drive was sector 0x3F. Because this starting offset was an odd number, it could cause performance issues on large-sector drives because of misalignment between the partition and the physical sectors. In Windows Vista, the default starting offset will generally be sector 0x800.

If in the future we go to 16K or even 1MB sectors, you can image an old disk onto a new one, and the partition will still be aligned.

The half-MB blocks on SSDs that Robert mentioned also makes sense. If you're going to realign something, pick a nice round number.

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MBR malware is now taking advantage of that unused second 1k of space to store code, wonderful. –  Moab Sep 16 '11 at 20:04
    
There were still 62 sectors that malware could use previously. Any malware author worth his salt could cram something in there ;). –  Bigbio2002 Sep 16 '11 at 20:29
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I assume that is a precautionary measurement because of disk devices that use internally larger block sizes. This is especially important for solid state disks that usually groups the cells internally to pages of 512KB. Without a correct alignment data (write) rates would decrease massively.

For details of SSD internals see http://www.anandtech.com/show/2738/5

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