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From: damien@lugnut.stu.rpi.edu (Damien Neil)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: What disk for swap partition
Date: 21 Oct 1995 16:50:37 -0400
Organization: Rensselaer Polytechnic Institute
Lines: 22
Message-ID: <46bmet$3lq@lugnut.stu.rpi.edu>
References: <46b9sa$2ia@news-s01.ny.us.ibm.net>
NNTP-Posting-Host: lugnut.stu.rpi.edu
In article <46b9sa$2ia@news-s01.ny.us.ibm.net>, <mccrobi@ibm.net> wrote:
>The kernel is booted from the IDE drive. Only the root and the swap are on
>the IDE and everything else is on the SCSI-2 disk. Would I be better
>served to put the swap on the SCSI-2 disk since, as I understand it, IDE
>drives require the CPU to do the transfer?
In a word: yes.
By all means, put your swap on a SCSI disk if at all possible. IDE is
a less than optimal technology under the best of circumstances, and
FreeBSD's IDE drivers are not all that good either.
>Is this a mute point in that
>the transfer to the controller is as fast as the to the SCSI-2 disk using
>DMA? (I know the DMA will free the CPU for other processing.)
FreeBSD will not do DMA to an IDE (Fast-ATA, or EIDE, actually) controller.
This causes accesses to IDE disks to incur a huge performance hit.
Use the IDE drive for seldom-accessed data.
- Damien