IDE -- mount partitions for better performance

Polytropon freebsd at
Tue Mar 15 20:59:16 UTC 2011

On Tue, 15 Mar 2011 15:17:34 -0400, freebsd_user at wrote:
> > did I get it right? You have four hard disks?
> Yes, four separate HDD's

I assume you have two on each of the two lines:

	ad0 = primary master

	ad1 = primary slave

	ad2 = secondary master

	ad3 = secondary slave

This is how they would be connected:



> Are you suggesting something similar to:
> /dev/ad4s1a for /
> /dev/ad4s2a for /tmp
> /dev/ad4s3a for /usr
> /dev/ad4s4a for /var

No. You don't need to even slice the disks (if you're running
FreeBSD only, use "dangerously" dedicated layout). But if you
require compatibility, make the following layout (just a

	ad0s1a = /
	ad0s1d = /usr

	ad1s1a = /tmp
	ad1s1b = swap

	ad2s1a = /var

	ad3s1a = /home

Keep in mind that performance "across" ad0 and ad2 is best.
Masters are always good. Slaves are slower. Using primary
and secondary in parallel works good, working on a master
and a slave simultanously is worse.

So you have the chance to put different subtrees (for example
/usr/obj or /usr/src) on different partitions, drives and
lines if needed. The positioning always depends on how much
activity you expect on the certain file systems. You did get
this idea already.


	/usr is on prim. master, 2nd partition
	/usr/obj is mounted to /var/uobj on sec. master, 2nd partition

You could also add - with the known limitations (fixed size) -
other partitions depending on R/W activity, for example if
you need /export or /opt.

I have successfully used similar approaches in the past, also
using (P)ATA disks, but I had them on a separate controller
(also 2 ATA channels, just as you use them from the mainboard).

If you omit the slicing step, all examples remove "s1".

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

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