Gregory Leblanc writes:
...
> > I know that the Linux kernel auto-detects the SCSI devices on boots
> > and assigns them
> >
> > /dev/sda to the first one
> > /dev/sdb to the second one ...
> >
> > and so on.
>
> Yep. Lots of planning done there. :-)
>
> > Doesn't this put a kink in your plans if you remove a disk physically
> > and then restart the system? I mean, what if the failiure on the disk
> > is something like smoke coming out of the drive bay and the next time
> > you reboot the kernel doesn't even see the device?
>
> If you're using just the SCSI drives, yes, it screws everything up.
>
> > Is there a way to hard code /dev/sda to Target ID N and /dev/sdb to
> > Target ID M so that in case N fails, your old /dev/sdb doesn't show up
> > as /dev/sda when you reboot?
>
> Sort of. There are some "devfs" patches that make the /dev filesystem MUCH
> cleaner, and they keep disk at the same location, even when other disks are
> removed. It does break a few things though. I don't think it currently
> works with RAID, at least not on 2.2.x
>
> > The setup I'm envisioning is a 2.2.16 kernel with the latest patches,
> > a single SCSI bus with 2 hard drives in a RAID 1 configuration. If it
> > makes a difference, the system will NOT boot from these disks.
>
> Well, with persistent superblocks, you don't have anything to worry about.
> The kernel will just detect your RAID sets, and configure them. Then, since
> /etc/fstab is pointed at /dev/mdX rather than /dev/sdX, you don't have to
> worry about SCSI drives changing. HTH,
Thanks for the response. Unfortunately, I don't think this setup
would help my situation very much, because this is on a shared SCSI
bus configuration. Autodetection screws everything up, because when the
second machine is booted, it shouldn't have "permission" to access the
disks.
Is there a way for me to take advantage of the persistent superblock
without kernel auto detection? Basically, I don't want to start the
RAID device until I say, "GO" (after we are sure the peer system is no
longer accessing the devices.)
-Eric.
