On Wed, 30 Jun 2010 07:54:55 +0200 (CEST) Mikael Abrahamsson <swmike@xxxxxxxxx> wrote: > On Wed, 30 Jun 2010, Roman Mamedov wrote: > > > dd if=/dev/zero of=zerofile bs=1M count=2048 conv=fdatasync,notrunc > > To be a bit more sure about accurate measurement, make sure the amount of > data you're transferring is twice the amount of RAM in the machine, the > above is only 2 gigs of data. This is not necessary. See the dd man page about the conv=fdatasync switch. You can even test with just 256 MB this way, and still get an extremely accurate result. Three consecutive runs with "count=256" on a machine with 4GB of RAM: 268435456 bytes (268 MB) copied, 4.76846 s, 56.3 MB/s 268435456 bytes (268 MB) copied, 4.79682 s, 56.0 MB/s 268435456 bytes (268 MB) copied, 4.79307 s, 56.0 MB/s -- With respect, Roman
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