John said:
Intel has an "Acronis AlignTool" for correction an NTFS formatting
problem in Windows XP. Something about the starting sector being 63
causing every read to access the disk twice. If I recall correctly,
my Macrium Reflect backup took 58 seconds before using that tool. It
took 30 seconds after.
I wonder if my first SSD could have benifited by the same tool.
On older OSes, they use the CHS information the disk gives them.
Even though, in practical terms, the disk uses LBA for normal usage.
The "fake" CHS info, says the disk has 63 sectors per track. That
applies to the larger disks. (We don't really know how many sectors
there are per track, but the number isn't 63. It hasn't been 63 for
about twenty years or so.)
Flash memory chips, on the other hand, are aligned to power_of_two
quantities.
Windows 7 or Vista solves this, by aligning the first partition to
an offset of a megabyte or two. Which is a power_of_two number of
sectors. This improves the odds that a disk cluster, aligns with
the flash units of storage. And the idea is, there are fewer
fractional operations required, on average.
If you change the alignment, then your older partition management
tools will complain. For example, if I used that AlignTool here,
Partition Magic would stop working, and PTEDIT32 would as well.
Which in the scheme of things, is a small loss. (I could replace
it with a free partition manager.)
And yes, the SSDs share characteristics, so what helps your new one,
would have helped the old one too. The page size may have doubled,
between the old and new one. But the same issues still occur, and
alignment helps.
If you'd primed the SSD on a Windows 7 (or even the release preview
version of Windows 8), then chances are it would be aligned as well.
The AlignTool's benefit, is the ability to correct a file system
that already has data on it. If the SSD has nothing on it, then
you can also create a fresh partition as a means to align it.
And then copy the data over after that. If you prepped in WinXP,
the partition would be misaligned. If you manually entered the
information into the MBR yourself, then your next battle would be
getting a formatter to like what you'd done. In terms of the
tools I've got here, I'd have a hard time cobbling together a
solution manually. (I could change the offset with PTEDIT32,
but then the question would be, whether the WinXP formatter
would have a heart failure on seeing that alignment.)
*******
There's a procedure here, for checking the alignment. It requires
"NAND erase block size" and "NAND page size", and that info comes
from the SSD maker. (It's actually determined by the flash chips
themselves.) There was also a web site with a "worksheet", where
you plugged the numbers in, and it told you whether the alignment
was good or not. If you prepped a drive in Windows 7, it might
be worthwhile verifying the job was done right (at least, the
first time).
http://www.ehow.com/how_8651274_test-ssd-alignment.html
Paul
