Hello, I now tested RAID1 together with grub by unplugging the 1st disk (to be sure, I tested with the 2nd as well).
As you can read further up in this thread I did run 'grub-install --no-floppy /dev/sdb' to install the boot-loader in the MBR of the 2nd disk /dev/sdb. Then I halted the computer and unplugged the disk connected to the SATA0 port. The system booted without problem and /proc/mdstat displays only 1 active device in the RAID1: # BEGIN-CLI deb64a:~$ cat tmp/mdstat_unplug0.txt Personalities : [raid1] md3 : active raid1 sda6[1] 106896384 blocks [2/1] [_U] md2 : active raid1 sda5[1] 46877568 blocks [2/1] [_U] md1 : active raid1 sda2[1] 1951808 blocks [2/1] [_U] md0 : active raid1 sda1[1] 64128 blocks [2/1] [_U] unused devices: <none> # END-CLI After halting the system I plugged the SATA0 disk in again and booted. I had to hot add the sda? partitions to the RAID1 with mdadm: # BEGIN-CLI deb64a:~# mdadm /dev/md0 -a /dev/sda1 mdadm: hot added /dev/sda1 deb64a:~# mdadm /dev/md1 -a /dev/sda2 mdadm: hot added /dev/sda2 deb64a:~# mdadm /dev/md2 -a /dev/sda5 mdadm: hot added /dev/sda5 deb64a:~# mdadm /dev/md3 -a /dev/sda6 mdadm: hot added /dev/sda6 # END-CLI It takes about 40 min to rebuild the 100 GB /dev/md3. After that /proc/mdstat shows a clean RAID1: # BEGIN-CLI deb64a:# cat tmp/mdstat_ok.txt Personalities : [raid1] md3 : active raid1 sda6[0] sdb6[1] 106896384 blocks [2/2] [UU] md2 : active raid1 sda5[0] sdb5[1] 46877568 blocks [2/2] [UU] md1 : active raid1 sda2[0] sdb2[1] 1951808 blocks [2/2] [UU] md0 : active raid1 sda1[0] sdb1[1] 64128 blocks [2/2] [UU] unused devices: <none> # END-CLI Then I repeated the same, but this time I unplugged the disk connected to the SATA1 port. The system did boot without problems. Comparing the output of dmesg after unplugging SATA0 vs. SATA1 shows that I unplugged different disks each time: # BEGIN-CLI deb64a:~$ diff tmp/dmesg_unplug[01].txt | grep 'sd[ab]' #< SCSI device sda: 312581808 512-byte hdwr sectors (160042 MB) #> SCSI device sda: 312579695 512-byte hdwr sectors (160041 MB) #< SCSI device sda: 312581808 512-byte hdwr sectors (160042 MB) #> SCSI device sda: 312579695 512-byte hdwr sectors (160041 MB) #< sd 1:0:0:0: Attached scsi disk sda #> sd 0:0:0:0: Attached scsi disk sda # END-CLI Another proof is the output of mdadm -D /dev/md0' after the reboot with readded disk but before doing the hot add: # BEGIN-CLI deb64a:# cat tmp/mdadm_replug0.txt | tail -n 3 Number Major Minor RaidDevice State 0 0 0 - removed 1 8 17 1 active sync /dev/sdb1 deb64a:# cat tmp/mdadm_replug1.txt | tail -n 3 Number Major Minor RaidDevice State 0 8 1 0 active sync /dev/sda1 1 0 0 - removed # END-CLI As written before, the MBRs on /dev/sda and /dev/sdb are not identical. # BEGIN-CLI deb64a:~# dd if=/dev/sda bs=512 count=1 | od -v | head -n 8 1+0 records in 1+0 records out 512 bytes (512 B) copied, 2.1e-05 seconds, 24.4 MB/s 0000000 044353 150220 000274 175574 003520 017520 137374 076033 0000020 015677 050006 134527 000745 122363 136713 003676 002261 0000040 067070 076000 072411 101423 010305 172342 014315 172613 0000060 143203 044420 014564 026070 173164 132640 132007 001003 0000100 000377 020000 000001 000000 001000 110372 173220 100302 0000120 001165 100262 054752 000174 030400 107300 107330 136320 0000140 020000 120373 076100 177474 001164 141210 137122 076577 0000160 032350 173001 100302 052164 040664 125273 146525 055023 deb64a:~# dd if=/dev/sdb bs=512 count=1 | od -v | head -n 8 1+0 records in 1+0 records out 512 bytes (512 B) copied, 2.2e-05 seconds, 23.3 MB/s 0000000 044353 010220 150216 000274 134260 000000 154216 140216 0000020 137373 076000 000277 134406 001000 122363 020752 000006 0000040 137000 003676 002070 005565 143203 100420 177376 072407 0000060 165763 132026 130002 135401 076000 100262 072212 001003 0000100 000377 020000 000001 000000 001000 110372 173220 100302 0000120 001165 100262 054752 000174 030400 107300 107330 136320 0000140 020000 120373 076100 177474 001164 141210 137122 076577 0000160 032350 173001 100302 052164 040664 125273 146525 055023 # END-CLI On Sun, May 21, 2006 at 05:21:17PM +0200, Goswin von Brederlow wrote: > Alexander Sieck <[EMAIL PROTECTED]> writes: > > > That is, also after changing sda to sdb in device.map, the > > two MBRs are not identical. > > > > Maybe Goswin, or somebody else who enabled booting from both > > disks with RAID1 and grub, can give the output of > > 'dd if=xxx[ab] bs=512 count=1 | od' on their system. > > I just dded the mbr from sda to all raid devices making them identical > the last time I installed. > After knowing that both disks are bootable with non identical MBRs, now it would be interesting to see, whether dd'ing the MBR of the 1st disk to the other disks also works. I leave this test for somebody else:-) For the sake of completeness. The Software-RAID HOWTO on http://www.tldp.org/HOWTO/html_single/Software-RAID-HOWTO/ states as well, that RAID(1) works together with grub. # BEGIN-QUOTE 7.3 Booting on RAID ... If you are using grub instead of LILO, then just start grub and configure it to use the second (or third, or fourth...) disk in the RAID-1 array you want to boot off as its root device and run setup. And that's all. For example, on an array consisting of /dev/hda1 and /dev/hdc1 where both partitions should be bootable you should just do this: grub grub>device (hd0) /dev/hdc grub>root (hd0,0) grub>setup (hd0) ... # END-QUOTE Alexander -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]