File system blocks alignment
scottl at samsco.org
Sat Jan 2 00:03:12 UTC 2010
On Jan 1, 2010, at 3:47 PM, Poul-Henning Kamp wrote:
> In message <201001012153.44349.pieter at degoeje.nl>, Pieter de Goeje
>> That yielded some pretty spectacular results. [...]
>> Performance for restore was abysmal in the unaligned case, easily
>> being 10
>> times slower than aligned restore. Newfs was about 5 times as slow.
> That is what I expected, only I didn't expect a factor 14 in
It's all about read latency in the read-modify update operation.
While buses and caches and gotten steadily faster over the past 20
years, disk platters and hysteresis fields have not. This is also why
buying faster platters is always an important consideration for
overall performance; a desktop or laptop with 5400RPM drives will feel
significantly slower than one with 7200RPM drives, and 15K RPM drives
still rule the roost.
Thanks a lot for doing the testing. Would it be possible to publish
these results somewhere that can be linked to in the future?
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