DragonFly users List (threaded) for 2008-07
DragonFly BSD
DragonFly users List (threaded) for 2008-07
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Hammer - block size

From: "Jim Wilcoxson" <jim@xxxxxxxxxxx>
Date: Fri, 11 Jul 2008 17:18:54 -0400 (EDT)

I've been reading the DF mail archives the last few days about Hammer, and
it looks very good!

Today I saw a review of 1TB hard drives, and there are some interesting
charts on sequential I/O performance showing that the "sweet spot" is
128K, across many vendors' drives:


On some drives, there is not much difference: 110MB/s for 64K vs 120MB/s
for 128K.  But with other drives (WD), the difference is 105MB/s for 64K
vs 185MB/s for 128K.

I read that the Hammer block size was changed from 16K to 64K; maybe you
should consider running your blog benchmarks at 128K to see if that's a
better block size.  I realize there is probably a trade-off between the
block size and wasting too much space for smallish files, unless Hammer
uses partial blocks for small files.  Does it do that?

The tests were run with SATA 2 controllers in PCI-X slots because SATA 1
controllers and regular PCI slots aren't fast enough to handle these

Good luck with your 2.0 release!

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