Date: Sun, 29 Oct 2000 23:05:58 -0500 From: Brian McGovern <mcgovern@spoon.beta.com> To: qa@freebsd.org Cc: hackers@freebsd.org Subject: DMA/66 not available for secondary IDE bus? Message-ID: <200010300405.e9U45wu75483@spoon.beta.com>
next in thread | raw e-mail | index | archive | help
This may be intentional, but I've noticed that if you have a non-UDMA66 device on the primary IDE bus, FreeBSD 4.x does not allow you to have UDMA66 on the secondary bus. To wit, if you had a configuration similar to: Primary bus Older (UDMA33 or earlier) IDE boot disk CD ROM Secondary bus 15GB UDMA 66 disk 15GB UDMA 66 disk then even your 16GB drives can not be UDMA 66, and are limited to the UDMA (or less!) speed provided on the primary bus. This is particularly troubling if one were to use vinum to try to do a mirror, as you will not get optimum performance from the drives. One could argue that shuffling devices around and upgrading the boot drive would solve the problem on one of the 15GB disks, but its still not really an optimal solution, as you'd have to move your CD rom on to the secondary bus, which would kill the other 15GB drive. Any possibility that we could 'unhook' the two PCI buses, and allow the secondary to go to UDMA66 if the first is down at UDMA 33 or slower? -Brian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-qa" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200010300405.e9U45wu75483>