Re: Strage buffer behaviour

[Tomasz Chmielewski]

Denys Vlasenko wrote:

> On Sunday 11 November 2007 11:33, Tino Keitel wrote:
> > The dd command reads 100 MB from each partition two times in a row. It
> > looks like sda1 and sda2 are not bufferd (the first 4 dd runs), but
> > sda3 and sda4 are (the last 4 dd runs).
> >
> > The computer is a Mac mini with a 2,5" SATA hard disk. The first 2
> > partitions contain EFI and MacOS X, and are unused in Linux. The last 2
> > partitions are an ext3 partition for / and an LVM for the rest of the
> > sytem.
> >
> > Any hints how the dd/buffering behaviour could be explained? The system
> > was mostly idle, and the numbers are reproducible across reboots.
>
> IIRC only mounted partitions' reads are cached.

Or, in general, those devices which kernel actually "uses" (mounted, but 
also LVM, RAID, which don't have to be mounted to get cached).


--
Tomasz Chmielewski
http://lists.wpkg.org
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