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Old 09-15-2012, 06:15 PM   #16
jtsn
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Quote:
Originally Posted by TobiSGD View Post
OK, I shouldn't have said physical sector size, but flash block erase boundaries. Those are usually between 128K-512K and are those that have the performance impact when writing to the SSD. Partitions should be aligned to this erase boundaries
SSD controllers don't export these boundaries to the user space. There is no 1:1 mapping, because this would incur a heavy read-modify-write penalty. So you can't align partitions to erase block boundaries anyway.

If you randomly write a 4K sector anywhere on a SSD, it of course lands in a completely different erase block on the flash, than the sector before and behind it.
 
Old 09-16-2012, 08:56 AM   #17
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So how do you explain the massive performance impact on SSDs that don't have aligned partitions?
 
Old 09-16-2012, 10:02 AM   #18
pan64
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here is a small explanation: http://superuser.com/questions/39391...ould-i-need-it
 
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Old 09-17-2012, 07:04 AM   #19
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Quote:
Originally Posted by TobiSGD View Post
So how do you explain the massive performance impact on SSDs that don't have aligned partitions?
You have to align them to 4K (8 logical sectors) just like advanced format hard disks. Of course, 1M (2048 logical sectors) works too, because 2048 is a multiple of 8.
 
Old 02-06-2013, 02:39 AM   #20
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does that mean I have to remove all data and rewrite all partition ?
 
  


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