Re: IDE -- mount partitions for better performance



On Tue, 15 Mar 2011 15:17:34 -0400, freebsd_user@xxxxxxxxxxxx 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:

=====primary=====ad0-----ad1

=====secondary===ad2-----ad3



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
suggestion):

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.

Example:

/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".





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