Date: Fri, 06 Dec 2002 09:42:42 -0500 From: Chris Shenton <chris@shenton.org> To: questions@freebsd.org Cc: hardware@freebsd.org Subject: amr AMI MegaRAID IDE card: "spare" drive as slave? Message-ID: <87isy79pjx.fsf@thanatos.shenton.org>
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I have an AMI MegaRAID sold by Dell as a CERC ATA100; it has 4
discreet channels of IDE and can do RAID 0, 1, 5, or 10. I've been
running it as RAID 1 for a couple months no problem, with a pair of
WD1200JB 120G disks and a pair of 20G disks -- two logical
partitions.
The man page only talks about the amr driver for SCSI so I'm guessing
that the interface to the computer looks identical to the AMI SCSI
cards, but the disk interface is simply IDE.
chris@pectopah_34% dmesg|grep am
amr0: <AMI MegaRAID> mem 0xfeb00000-0xfeb0ffff irq 5 at device 4.0 on pci0
amr0: <CERC ATA100/4ch> Firmware 6.61, BIOS 1.01, 16MB RAM
amrd0: <MegaRAID logical drive> on amr0
amrd0: 19068MB (39051264 sectors) RAID 1 (optimal)
amrd1: <MegaRAID logical drive> on amr0
amrd1: 114428MB (234348544 sectors) RAID 1 (optimal)
Mounting root from ufs:/dev/amrd0s1a
For performance, naturally each disk is an IDE master on its own IDE
cable.
I'd like to get another disk or two and use them as hot spares so if
one of the existing drives goes bad the amr controller can just
rebuild the data on the spare. Can such a spare run as the IDE
channel slave without impacting performance of the master? My thinking
is that the controller should send no data to the slave unless the
master dies so it shouldn't slow the master (and hence the RAID
volume) but I don't know enough about how this hardware works.
Any info would be most helpful. Thanks.
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