Re: RAID 1 and grub
Bill Davidsen wrote: Richard Scobie wrote: A followup for the archives: I found this document very useful: http://lists.us.dell.com/pipermail/linux-poweredge/2003-July/008898.html After modifying my grub.conf to refer to (hd0,0), reinstalling grub on hdc with: grub device (hd0) /dev/hdc grub root (hd0,0) grub (hd0) and rebooting with the bios set to boot off hdc, everything burst back into life. I shall now be checking all my Fedora/Centos RAID1 installs for grub installed on both drives. Have you actually tested this by removing the first hd and booting? Depending on the BIOS I believe that the fallback drive will be called hdc by the BIOS but will be hdd in the system. That was with RHEL3, but worth testing. The line: grub device (hd0) /dev/hdc simply means treat /dev/hdc as the first _bios_ hard disk in the system. This way when grub writes to the MBR of hd0, it will be in fact writing to /dev/hdc. The reason the drive must be referenced as hd0 (and not hd2) is because grub enuerates drives according to the bios, and therefore the drive from which the bios is currently booting is _always_ hd0. - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
Richard Scobie wrote: A followup for the archives: I found this document very useful: http://lists.us.dell.com/pipermail/linux-poweredge/2003-July/008898.html After modifying my grub.conf to refer to (hd0,0), reinstalling grub on hdc with: grub device (hd0) /dev/hdc grub root (hd0,0) grub (hd0) and rebooting with the bios set to boot off hdc, everything burst back into life. I shall now be checking all my Fedora/Centos RAID1 installs for grub installed on both drives. Have you actually tested this by removing the first hd and booting? Depending on the BIOS I believe that the fallback drive will be called hdc by the BIOS but will be hdd in the system. That was with RHEL3, but worth testing. -- Bill Davidsen [EMAIL PROTECTED] Woe unto the statesman who makes war without a reason that will still be valid when the war is over... Otto von Bismark - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
Bill Davidsen wrote: Have you actually tested this by removing the first hd and booting? Depending on the BIOS I believe that the fallback drive will be called hdc by the BIOS but will be hdd in the system. That was with RHEL3, but worth testing. Hi Bill, I did not try this particular combination. I shut the box down, removed the failed drive (hda) and installed it's replacement and proceeded from there. Once I had discovered that hdc had no grub installed, after running: grub device (hd0) /dev/hdc grub root (hd0,0) grub setup (hd0) I set the BIOS to boot from hdc and it all worked. Regards, Richard - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
On Wed, Jan 30, 2008 at 06:47:19PM -0800, David Rees wrote: On Jan 30, 2008 6:33 PM, Richard Scobie [EMAIL PROTECTED] wrote: FWIW, this step is clearly marked in the Software-RAID HOWTO under Booting on RAID: http://tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.3 A good an extesive reference, but somewhat outdated. BTW, I suspect you are missing the command setup from your 3rd command above, it should be: # grub grub device (hd0) /dev/hdc grub root (hd0,0) grub setup (hd0) I do not grasp this. How and where is it said that two disks are involved? hda and hdc should both be involved. Best regards keld - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
Keld Jørn Simonsen wrote: # grub grub device (hd0) /dev/hdc grub root (hd0,0) grub setup (hd0) I do not grasp this. How and where is it said that two disks are involved? hda and hdc should both be involved. There are not two disks involved in this instance. This is used in the scenario where the primary disk in the RAID1 (/dev/hda), already has grub installed in the MBR and you wish to install it on the secondary drive (/dev/hdc). This then allows for a failed primary drive to be removed and the machine to boot from the secondary - (may need BIOS to be set to boot from secondary drive). As an aside, after last weeks discovery that the Fedora 8 install had not installed grub on the secondary drive, as part of a RAID 1 install, some cursory Googling and searching Redhat's Knowledge base leads me to believe that this may well be normal for all Redhat (RHEL/Fedora) RAID1 installs. One has nothing to lose by installing grub on the second drive in this case and it may save some delay in recovery on losing the primary, although as has been pointed out, it is best practice to test missing drives as part of initial install testing. Regards, Richard - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
Richard Scobie wrote: David Rees wrote: FWIW, this step is clearly marked in the Software-RAID HOWTO under Booting on RAID: http://tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.3 The one place I didn't look... Good - I hope you'll both look here instead: http://linux-raid.osdl.org/index.php/Tweaking%2C_tuning_and_troubleshooting#Booting_on_RAID David - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
On Jan 30, 2008 2:06 PM, Richard Scobie [EMAIL PROTECTED] wrote: hda has failed and after spending some time with a rescue disk mounting hdc's /boot partition (hdc1) and changing the grub.conf device parameters, I have no success in booting off it. I then set them back to the original (hd0,0) and moved hdc into hda's position. Booting from there brings up the message: GRUB hard disk error Have you tried re-running grub-install after booting from a rescue disk? -Dave - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
David Rees wrote: Have you tried re-running grub-install after booting from a rescue disk? -Dave Hi David, I have but although I can advance further it seems that the BIOS is doing some strange things as well, switching drive ordering around. With a new hda installed and partitioned, ready to be rebuilt, the good drive, hdc installed, the grub.conf modified to address (hd2,0) - I have an hdb installed also, and grub installed on hdc, booting with the BIOS set to start on hdc hangs with the message grub stage2 then drops to a grub prompt. I then enter kernel (hd0,0)/vmlinuz and it finds the kernel. I would have expected this to be on (hd2,0). Next, boot root=/dev/md2, boot root=/dev/hdc3 or boot root=/dev/hda3 all result in the kernel booting then panicing with a cannot open root device. I suspect you are correct that the Fedora installer, having built and installed to RAID1, does not finish the job by installing grub on the second drive. While it is not a problem with this particular box to do a reinstall, it does not inspire confidence for a number of others that I have. This is the first time I have lost the primary member of a RAID1, having replaced secondary members a number of times without issue. Regards, Richard - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
A followup for the archives: I found this document very useful: http://lists.us.dell.com/pipermail/linux-poweredge/2003-July/008898.html After modifying my grub.conf to refer to (hd0,0), reinstalling grub on hdc with: grub device (hd0) /dev/hdc grub root (hd0,0) grub (hd0) and rebooting with the bios set to boot off hdc, everything burst back into life. I shall now be checking all my Fedora/Centos RAID1 installs for grub installed on both drives. Regards, Richard - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
David Rees wrote: FWIW, this step is clearly marked in the Software-RAID HOWTO under Booting on RAID: http://tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.3 The one place I didn't look... BTW, I suspect you are missing the command setup from your 3rd command above, it should be: # grub grub device (hd0) /dev/hdc grub root (hd0,0) grub setup (hd0) That is correct. Regards, Richard - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: RAID 1 and grub
On Jan 30, 2008 6:33 PM, Richard Scobie [EMAIL PROTECTED] wrote: I found this document very useful: http://lists.us.dell.com/pipermail/linux-poweredge/2003-July/008898.html After modifying my grub.conf to refer to (hd0,0), reinstalling grub on hdc with: grub device (hd0) /dev/hdc grub root (hd0,0) grub (hd0) and rebooting with the bios set to boot off hdc, everything burst back into life. FWIW, this step is clearly marked in the Software-RAID HOWTO under Booting on RAID: http://tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.3 If it appears that Fedora isn't doing this when installing on a Software RAID 1 boot device, I suggest you open a bug. BTW, I suspect you are missing the command setup from your 3rd command above, it should be: # grub grub device (hd0) /dev/hdc grub root (hd0,0) grub setup (hd0) I shall now be checking all my Fedora/Centos RAID1 installs for grub installed on both drives. Good idea. Whenever setting up a RAID1 device to boot from, I perform the above 3 steps. I also suggest using labels to identify partitions and testing the two failure modes and that you are able to boot with either drive disconnected. -Dave - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
