[arch-general] GPT slower than MBR, although both are properly aligned?
registo.mailling at gmail.com
Sat Jan 22 17:29:29 EST 2011
You need to consider the structures that are written at the start of the
partition, aligning only the partition start may not be enough (read, it
is not the partition start you need to align). You need to consider the
amount of data these structures use so the data part of the partition is
aligned to flash sector boundaries. I have seen an explanation of this
somewhere (for ext3 I think) and it was a little tricky, it needs a
really good understanding of the filesystem you are going to use.
I don't know if all vendors use the same sector/unit size, however for
reading the alignment should not matter (which is what you are doing
with hdparm -tT, the T part is only an indication of the read speed from
cache so it's probably even less meaningful).
It is the writes to disk that are affected if they are not aligned to
the flash sectors so I guess there is something else going on there.
I may be wrong though ... it would not the the first time :p
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