Date: Tue, 11 Jul 2000 12:26:57 -0700 (PDT) From: Linh Pham <lplist@q.closedsrc.org> To: Rahul Siddharthan <rsidd@physics.iisc.ernet.in> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Vinum/RAID-5 on IDE disks Message-ID: <Pine.BSF.4.21.0007111217270.91175-100000@q.closedsrc.org> In-Reply-To: <20000712004443.A6134@physics.iisc.ernet.in>
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It's always best to separate heavy I/O drives (mainly hard drives) onto separate IDE channels. But, that doesn't always mean that you get a whole lot more performance that way. Remember that a standard UltraDMA controller can handle up to 33MB/s per channel, ATA/66 doubles that, and finally ATA/100 brings it up to 100MB/s. Also remember that hard drives usually cannot soak up the entire ATA channel, but some drives can. But also another note is that only one drive can communicate on a specific IDE channel at any given time. This might reduce the overall thoroughput, but again, it's not always going to be the bottleneck. // Linh Pham // // Proud supporter of FreeBSD and OpenBSD // FreeBSD - http://www.freebsd.org // OpenBSD - http://www.openbsd.org /* "Oregon, n.: Eighty billion gallons of water with no place to go on Saturday night." */ On Wed, 12 Jul 2000, Rahul Siddharthan wrote: > On a system with 2 IDE buses and 4 disks (2 per bus), is it a good > idea to use RAID 5 / Vinum? I read of issues regarding performance > and fault tolerance on linux raid when you put two disks on one bus, > and it sounded like that should apply to freebsd too, but I can't find > a specific mention in the vinum documentation. > > One problem mentioned there that if a disk goes down, it can take the > bus and therefore the other disk down with it: it doesn't matter if > the data on the other disk is safe and therefore the system can be > brought back up without data loss. But is there a likelihood of the > other disk being corrupted in such an event? > > If there are performance issues with slave disks, are they likely to > be show-stopping? Any real-world experiences? > > Thanks, > > Rahul. > > ps the linux document was > http://linuxdoc.org/HOWTO/Software-RAID-HOWTO-3.html > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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