adding disk moves ad0 to ad4

Arthur Chance freebsd at
Wed Feb 3 18:28:27 UTC 2010

Steve Franks wrote:
> Just curious, having read the handbook section talking about freebsd
> going straight to the hardware and skipping the bios for disk
> numbering, why then, if I stick a sata disk in 'sata0' on the
> motherboard, does it come up as ad0, but if I add a second disk in
> 'sata1' or 'pata0', on the next boot, I have no ad0, but ad4 and ad6?
> This seems to be the case with every mobo I've owned in the last 2
> years from a variety of mfr's.  Is there a way around this?  I don't
> care what it comes out as, as long as it stays put...  Since I have
> the only fbsd system at work, I tend to format alot of funky drives
> for people, and it gets anoying having to swap fstab's every time...

If you think ad4 and ad6 for your disks is odd take a look at this 
(slightly line wrapped) extract from my file server boot dmesg.

arthur at fileserver> grep ata /var/run/dmesg.boot | grep -v ITHREAD
atapci0: <JMicron AHCI controller> mem 0xf4100000-0xf4101fff irq 19 at
	device 0.0 on pci2
atapci0: AHCI Version 01.00 controller with 2 ports detected
ata2: <ATA channel 0> on atapci0
ata3: <ATA channel 1> on atapci0
atapci1: <JMicron JMB363 UDMA133 controller> port
	0xb300-0xb303,0xb400-0xb40f irq 16 at device 0.1 on pci2
ata4: <ATA channel 0> on atapci1
atapci2: <Intel AHCI controller> port
	0xea00-0xea03,0xeb00-0xeb1f mem 0xf4286000-0xf42867ff irq 19 at
	device 31.2 on pci0
atapci2: AHCI Version 01.20 controller with 6 ports detected
ata5: <ATA channel 0> on atapci2
ata6: <ATA channel 1> on atapci2
ata7: <ATA channel 2> on atapci2
ata8: <ATA channel 3> on atapci2
ata9: <ATA channel 4> on atapci2
ata10: <ATA channel 5> on atapci2
ad10: 476940MB <SAMSUNG HD501LJ CR100-12> at ata5-master SATA300
ad12: 953869MB <WDC WD10EAVS-00D7B1 01.01A01> at ata6-master SATA300
ad14: 953869MB <SAMSUNG HD103UJ 1AA01108> at ata7-master SATA300
ad16: 953869MB <SAMSUNG HD103UJ 1AA01108> at ata8-master SATA300
acd0: DVDR <ASUS DRW-2014S1T/1.00> at ata9-master SATA150

My SATA disks are ad{10,12,14,16}. This is a 2 year old Gigabyte server 
mobo, I can't remember the exact model off hand.

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