On Sat, Aug 03, 2002 at 07:26:29AM +1000, Neil Brown wrote: > On Thursday August 1, vindex@apartia.org wrote: > > > > I have a root raid1 partition on /dev/sda1 & /dev/sdb1 (swap on > > /dev/sda2 & /dev/sdb2). The server boots directly from the raid > > partition. > > > > Now /dev/sda1 and /dev/sda2 have both failed and been removed from the > > array and I am getting ready to replace the disk tonight. > > Lucky you :-) It went fast fortunately ;-) And yes, I am very lucky to have raid1 notify me by email through mdadm of a disk failure. FWIW the disk that is malfunctioning is a 3-month-old Fujitsu 15k 36G (MAM3367MP) which is an expensive server-grade disk. The reason I selected Fujitsu was because of reported quality problems on IBM disks and Fujitsu's good reputation on SCSI (their IDE line is bad however). I am looking for informed opinions on these disks and recommendations for future purchases. What are the most reliable SCSI disks out there? It must be: fast, affordable, reliable, (select any two ;-) > > > > What is the best way to proceed to minimize downtime? > > > > My concern is that if I power down and replace /dev/sda the machine > > won't be able to reboot without a rescue CD (lilo.conf has root=/dev/md0 > > and boot=/dev/md0) or will it? > > > > When the bios (Dell Poweredge 1500) will try /dev/sda's mbr and fail, > > will it then automatically try /dev/sdb? > > With most bioses I have seen you can explicitly tell it which device > to boot from. But cannot say for-sure about Dell Poweredge. Yes, I found it's in the SCSI bios itself. Very configurable. Unfortunately when I tried booting from /dev/sdb the screen filled with 010101010 instead of "lilo". And this is on debian unstable, having run lilo on /dev/md0 just prior booting. In fact I found that having root and boot set to /dev/md0 in lilo.conf does not allow me to boot my raid1 partition. However if I set root=/dev/sda all goes well. Any trick here? (both disks are identical) > > > > Or should I swap /dev/sdb on the scsi ribbon to have it take the first > > place and thus become /dev/sda or will this just confuse the kernel > > raid driver? (the letter on scsi drives is dependent on their place on > > the ribbon cable, isn't it?) > > It isn't the position on the ribbon cable. It is the position in the > scsi device number ordering. If you make sure the new drive has a > larger number than the old drive, the old drive will appear as sda. I'm really ashamed to have asked that one, memory lapse on my part. > > > > Alternatively I was thinking of booting with a rescue CD (after > > replacing /dev/sda) with the "root=/dev/md0", creating my partitions, > > running lilo and rebooting into production for final reconstruction. > > Would that be the safest bet? > > This sounds like the best bet to me. You do have to boot twice, but > if you try the other, less well understood (by you atleast) approach, > there is an even chance you will need to reboot a couple of times > anyway. Having failed to boot /dev/sdb this is what I ended up doing and all went well. Thanks for your help and ideas, cheers, -- ldm@apartia.org - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
