On Fri, 2006-03-31 at 23:34 -0600, Laurence Vanek wrote: > Craig White wrote: > > On Tue, 2006-03-28 at 08:05 -0700, Craig White wrote: > > > >> On Mon, 2006-03-27 at 21:43 -0600, Laurence Vanek wrote: > >> > >>> Greetings - > >>> > >>> To my surprise, fresh install of FC5 with RAID 1 configured at install > >>> time went without a hitch. I have /dev/md0 defined on /boot > >>> partitions. It boots fine with this setup. > >>> > >>> I had my FC4 system setup this exact way except I found that I had to > >>> manually install grub on one of the disks to permit booting off either > >>> one if the other is down. > >>> > >>> Does anyone know of a way to check for the presence of grub on each > >>> drive (obviously its on hda since it boots presently) to see if this > >>> needs to be done for FC5 also without powering down each drive in turn & > >>> attempting to boot? > >>> > >> ---- > >> thought I should post against the right thread > >> > >> just an untested thought... > >> > >> bb if=/dev/sda of=/tmp/sda-bootblock.bin bs=512 count=1 > >> bb if=/dev/sdb of=/tmp/sdb-bootblock.bin bs=512 count=1 > >> > >> diff /tmp/sda-bootblock.bin /tmp/sdb-bootblock.bin > >> > >> Thinking... > >> > >> - substitute different values for sda/sdb as fits > >> - the first 512 bytes on each drive are the boot (perhaps less, someone > >> will surely correct me...it might just be the first 256 or 384 bytes) > >> - if they are the same (i.e. grub has been installed on both), there > >> will be no diff > >> > >> otherwise... > >> > >> grub-install /dev/sdb > >> > >> Of course, the only way that you'll ever KNOW for sure that it's going > >> to work is to do a real simulation, i.e. disconnecting one drive, then > >> the other drive... > >> > > ---- > > not only wrong thread but as Paul so correctly points out. > > > > dd - NOT bb > > > > I am rapidly ingesting coffee but haven't figured out a mainline method > > so I am left to normal ingestion methods which apparently haven't quite > > caught up to my fingers or my brain. > > > > duh. > > > > Sorry > > > > Craig > > > > > Craig - > > results using bs=466 > ============ > [root@localhost tmp]# dd if=/dev/hda of=/tmp/hda-bootblock.bin bs=466 > count=1 > 1+0 records in > 1+0 records out > 466 bytes (466 B) copied, 7.6e-05 seconds, 6.1 MB/s > [root@localhost tmp]# dd if=/dev/hdc of=/tmp/hdc-bootblock.bin bs=466 > count=1 > 1+0 records in > 1+0 records out > 466 bytes (466 B) copied, 7.7e-05 seconds, 6.1 MB/s > [root@localhost tmp]# diff hda-bootblock.bin hdc-bootblock.bin > Binary files hda-bootblock.bin and hdc-bootblock.bin differ > ================ > > files also differ is bs=256, 128 > BUT for bs=64 we get no complaint from diff: > > ================ > [root@localhost tmp]# dd if=/dev/hda of=/tmp/hda-bootblock.bin bs=64 count=1 > 1+0 records in > 1+0 records out > 64 bytes (64 B) copied, 7.8e-05 seconds, 821 kB/s > [root@localhost tmp]# dd if=/dev/hdc of=/tmp/hdc-bootblock.bin bs=64 count=1 > 1+0 records in > 1+0 records out > 64 bytes (64 B) copied, 7.6e-05 seconds, 842 kB/s > [root@localhost tmp]# diff hda-bootblock.bin hdc-bootblock.bin > ================ ---- well - you sort of blew my theory right out of the water - thanks. the theory being, that the grub boot blocks on both drives should be the same - I guess that something is different on both drives but in theory, I was thinking that if it were installed... grub-install /dev/hda grub-install /dev/hdc then they should both be the same boot blocks. On yours, the boot blocks on /dev/hda were written by the installer (anaconda) and on /dev/hdc were written by you manually by issuing 'grub' command and stepping through it manually as I recall. ;-( Well, I'm glad it worked...sorry I was really of little help. Craig
