On Tue, 2004-08-17 at 07:14, Nigel Wade wrote: > Michael E. Webster wrote: > > Michael, > > > > Probably - I went with "ghost" because I had a boot floppy handy. > > You should not need to ghost. Add the new drive as a hot spare and md should > take care of building the new drive whilst the system is running (it does > need to be partitioned correctly first). > You are absolutely correct. I remember now why I ghosted the drive - it was our main mail server and we wanted to have a "good" drive with all of our data in case something went wrong during the rebuild. That's why I copied the drive and pulled it from the system. > > > > The main thing is to get the MBR from that first drive - without it, > > you're out of luck. > > > > In software RAID, the MBR is only written to the first drive, which > > really doesn't make sense. I would think that if you had the first > > drive fail, you should be able to boot off the second one - IMHO. > > > > > > Mike. > > > > > > I don't think that's right. > > In the case of lilo it writes MBRs such that each drive will boot from > itself, and either drive can work with the other removed. OTOH, due to the > way grub works, only one drive can be used as the boot device (each will try > to boot from the same drive). > > At least this was the case in RH9 which is the latest mirrored boot system > I've setup. It's entirely possible that lilo has since been broken so that > it no longer handles booting from mirrored disks. > I honestly don't know how lilo handles the MBRs in software RAID - I was talking about FC1 using grub. With grub only one drive can be used as the boot device. Thus, if your main boot device crashes - and you don't have the MBR copied onto the second drive you will have problems. For more information, I found this helpful: http://lists.us.dell.com/pipermail/linux-poweredge/2003-July/014331.html > -- > Nigel Wade, System Administrator, Space Plasma Physics Group, > University of Leicester, Leicester, LE1 7RH, UK > E-mail : nmw@xxxxxxxxxxxx > Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555 >
