2003-07-30 15:53:49

by Robert L. Harris

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Subject: devfs rescanning?



I have a system with 4 SCA drives. Originally they were:

/dev/sda -> scsi/host0/bus0/target0/lun0/disc
/dev/sdb -> scsi/host0/bus0/target1/lun0/disc
/dev/sdc -> scsi/host1/bus0/target0/lun0/disc
/dev/sdd -> scsi/host1/bus0/target1/lun0/disc

SDA drive was hot-pulled to test the raid failover and it worked great.
Next the box was rebooted after the drive was replaced (these systems
can hang or go real stupid when a drive is pulled). The drives remapped
as was expected. When it came back up the sd? entries had shifted up 1
as expected

/dev/sda -> scsi/host0/bus0/target1/lun0/disc
/dev/sdb -> scsi/host1/bus0/target0/lun0/disc
/dev/sdc -> scsi/host1/bus0/target1/lun0/disc

and when the drive was put back in it came up as sdd. Other than a
reboot is there any known way to get the drives back in the proper
order? Killing devfsd, removing the entries and restarting, etc didn't
do any good.

Robert


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2003-07-30 19:29:54

by Andrey Borzenkov

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Subject: Re: devfs rescanning?

> I have a system with 4 SCA drives. Originally they were:
>
> /dev/sda -> scsi/host0/bus0/target0/lun0/disc
> /dev/sdb -> scsi/host0/bus0/target1/lun0/disc
> /dev/sdc -> scsi/host1/bus0/target0/lun0/disc
> /dev/sdd -> scsi/host1/bus0/target1/lun0/disc
>
> SDA drive was hot-pulled to test the raid failover and it worked great.
> Next the box was rebooted after the drive was replaced (these systems
> can hang or go real stupid when a drive is pulled). The drives remapped
> as was expected. When it came back up the sd? entries had shifted up 1
> as expected

> /dev/sda -> scsi/host0/bus0/target1/lun0/disc
> /dev/sdb -> scsi/host1/bus0/target0/lun0/disc
> /dev/sdc -> scsi/host1/bus0/target1/lun0/disc
>
> and when the drive was put back in it came up as sdd. Other than a
> reboot is there any known way to get the drives back in the proper
> order? Killing devfsd, removing the entries and restarting, etc didn't
> do any good.

devfsd.conf:

REGISTER scsi/host0/bus0/target0/lun0/disc CFUNCTION GLOBAL mksymlink $devname
diska
REGISTER scsi/host0/bus0/target1/lun0/disc CFUNCTION GLOBAL mksymlink $devname
diskb
REGISTER scsi/host1/bus0/target0/lun0/disc CFUNCTION GLOBAL mksymlink $devname
diskc
REGISTER scsi/host1/bus0/target1/lun0/disc CFUNCTION GLOBAL mksymlink $devname
diskd

if you insist on calling them sda etc you may comment out MKOLDCOMPAT but
beware of consequences.

but this breaks anyway if SCSI host numbers change (e.g. if you plug in new
HBA) and for that there is no solution

-andrey