on 3-31-2008 6:30 AM Toby Bluhm spake the following: > Mail Administrator wrote: >> Thnaks john, >> >> u gave me a grt idea .. >> the second one >> seems quite interestin >> >> but i do have to get additional HDD and mirror my existing server which >> has jus one disk >> >> > > This was my procedure to mirror an existing single IDE disk RH4 system. > > YMMV. No guarantees. Not tested on Centos5. May eat all your data and > drink all your beer. > > Make a total backup before doing anything. > > IIRC the grub setup is what gave me the most problem. > > Hopefully, someone will chime in to point out any flaws here. > > ------------ > Current System/OS on single 10GB IDE disk > /dev/hda2 = swap @ 1GB > /dev/hda1 = / @ 9GB > Current system/OS is not in an LVM volume. > > 1. Install a 2nd identical disk as hdb > 2. fdisk: > /dev/hdb1 = 9000M ; /dev/hdb2 = 1000M ( rest of disk ) > part1 = type FD (raid) > part2 = type FD (raid) > 3. Create mirror device /dev/md10 for / with 2nd disk missing: > mdadm --create --level=1 --force --raid-devices=1 /dev/md10 /dev/hdb1 > 4. mke2fs -j /dev/md10 > 5. Create mirror device /dev/md11 for swap with 2nd disk missing: > mdadm --create --level=1 --force --raid-devices=1 /dev/md11 /dev/hdb2 > 6. mkswap /dev/md11 > > It may be safer to start step 7 from a rescue disk. > > 7. mkdir /z > 8. mount /dev/md10 /z > 9. cd / > 10. dump -a0f - . | ( cd /z ; restore -xvf - ) > 11. Update pertinent lines in > > /z/etc/grub.conf: > splashimage=(hd0,0)/boot/grub/splash.xpm.gz > root (hd0,0) > kernel /boot/vmlinuz-2.6.9-11.EL ro root=/dev/md10 rhgb > > /z/etc/fstab: > /dev/md10 / ext3 defaults 1 1 > /dev/md11 swap swap defaults 0 0 > > 12. Shutdown > 13. swap hdb & hda around > 14. Boot RHEL4 linux rescue ; let system find/mount RHEL Installations > 15. fdisk hdb to be identical to hda > 16. chroot /mnt/sysimage > 17. grub-install /dev/hda > 18. grub-install /dev/hdb > 19. Setup grub: > grub > root (hd0,0) > setup (hd0) > quit > 20. Create new initrd(s) to include modules raid, scsi, lvm, etc needed > at boot time: > mkinitrd --with=raid0 --with=raid1 --with=raid5 --with=aic79xx > /boot/initrd-2.6.9-22.EL.img.new > mv /boot/initrd-2.6.9-22.EL.img /boot/initrd-2.6.9-22.EL.img.old > cp /boot/initrd-2.6.9-22.EL.img.new /boot/initrd-2.6.9-22.EL.img > 21. Reboot to normal startup on the new mirrored / & swap. > > Step 21 needs to boot cleanly. Step 22 will remove your last chance to > revert to the old setup by installing the original boot disk as hda. > If something goes bad here, may need to restore from backup. > > 22. Add in 2nd disk to md10 mirror set: > mdadm --grow /dev/md10 --raid-devices=2 > mdadm --add /dev/md10 /dev/hdb1 > > 23. Add in 2nd disk to md11 mirror set: > mdadm --grow /dev/md11 --raid-devices=2 > mdadm --add /dev/md11 /dev/hdb2 > > You can monitor the sync process: > > cat /proc/mdstat: > md10 : active raid1 hdb1[2] hda1[0] > 8789632 blocks [2/1] [U_] > [>....................] recovery = 0.8% (77952/8789632) > finish=5.5min speed=25984K/sec > unused devices: <none> > > 24. System will be at normal state when mirror sync is finished > > One thing to add. Don't put the second drive as a slave to the first. Most times when a PATA drive goes down it will lock the entire channel until a reboot. The whole point of having the mirrors is to keep running on a drive fail. It is better to have it on the secondary master as hdc. Of course this doesn't apply to SATA or SCSI or their variants -- MailScanner is like deodorant... You hope everybody uses it, and you notice quickly if they don't!!!! -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 250 bytes Desc: OpenPGP digital signature URL: <http://lists.centos.org/pipermail/centos/attachments/20080331/8c2850a4/attachment-0005.sig>