IDE -- mount partitions for better performance

Polytropon freebsd at
Tue Mar 15 22:22:55 UTC 2011

On Tue, 15 Mar 2011 17:07:20 -0500, Adam Vande More <amvandemore at> wrote:
> Your statement about master being faster than a slave is simply not true for
> almost every scenario when using devices with same capabilites.  All
> master/slave really controls is enumeration, and shouldn't effect
> performance in and of itself.  Other variables can effect that of course,
> like using a slower device as an ATA Device-1 with a faster Device-0.  Even
> that example isn't ubiquitous as many, maybe most controllers are able to
> support mixed devices each in their fastest mode.

My statement originates back from individual experience
in settings where disks with different capabilities (esp.
very old + very new disk), as well as disk drive and an
optical drive with limited speed.

> The whole IDE device contention really isn't much of a bottle neck in this
> scenario.  It's only a big factor when there's *a lot* of simultaneous IO
> going to both, say dumping one disk to another.

That's true: When copying (or moving) data from one disk
to the other master->master seems to be faster than
master->slave (same line), if I remember correctly.

> The highest preforming setup in something like this is likely to be
> something along the lines of a 4-way /boot gmirror, and a 4-way gstripe with
> a smaller stripe size eg 32k across the remaining usable space.  If you
> aggregate your disk IO in this manner, IDE channel contention shouldn't be
> much of a bottleneck.

A good advice, I haven't thought of that (never tried, but
sounds achievable).

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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