Redhat 7.3 install does not recognize partitions when a software (md) RAID 1 array is running in degraded mode (i.e. one disk in mirror is not there). This is a problem because removing one disk in a mirror is a convenient way to save a full system backup before a system upgrade. Detail: I have been running redhat 7.1 with software mirroring of everything, including /boot and /. Tested quite a bit, works fine. I wanted to upgrade to 7.3. Doing a system upgrade can be very dangerous for a stable system. A convenient way to ensure rapid 100% rollback in case of a problem is to unplug a mirror and save it. If something goes wrong, just plug in the "saved mirror", boot from it, and you are all set. In a production environment this would work very well ... at least that was my plan. Unfortunately, it didn't work out that way. When the mirror is unplugged, the kernel on the 7.3 installation disk does not continue running in "degraded mode". Rather (it looks like to me) the /dev/md* devices are not installed. Therefore, the installer couldn't find any partitions to upgrade. If the mirror is plugged in and fully operational, the upgrade works fine. Normally, the kernel recognizes a "degraded" software RAID array and boots fine. Do a "raidhotadd" and it nicely duplicates the mirror. The kernel used in the installation process apparently does not do this. It rejects the "degraded" raid partitions. I'm not sure why this is the case. Perhaps it has to do with running in "recovery" mode. Q: Is there a driver that one can manually load to force mounting of the /dev/md* devices when they are degraded? Q: Are there command line arguments to the kernel which will force it to load the md devices even if they are degraded? I recommend that the option of installing to a "broken mirror" be supported in future releases of the installation software so that people can have an easy and effective rollback strategy using the unmodified half of a broken mirror. Thanks in advance, and let me know if I can provide any more info. Miguel -------- Original Message -------- Subject: upgrade 7.1->7.3 raid 1 not found From: "mth" <mth_redhat@xxxxxxx> Date: Tue, August 27, 2002 23:14 To: <anaconda-devel-list@xxxxxxxxxx> I installed 7.1 with software raid 1 some time ago (15 months?). Set up software raid 1 using normal 7.1 gui (disk druid?). Did some testing. Everything has worked great. I just tried to upgrade the system to redhat 7.3. Unfortunately, the raid partition is not seen by the installation software. If I tell it to do a systemupgrade it says that there are no linux partitions to upgrade. I tried text install, gui install, and hard disk install. No joy. Hard disk install doesn't make it as far because the installation system can't find the iso images ... presumably because the md driver isn't running. Thought 1: problem is caused by partition type being "FD" and not "82" or "83" Thought 2: I need a driver disk with the md driver to be able to access the "linux" partitions inside the "raid/md" partitions. (But it seems that this shouldn't be necessary since md support is built into the kernel.) Any suggestions/ideas? thanks in advance, mth -------------------------------------------------- Miguel Howard miguel@xxxxxxxxxxx c/Peña Primera 11-13 esc dcha 6B 37002 Salamanca España Spain -------------------------------------------------- telefono casa 923 27 10 82 movil 650 52 54 58 -------------------------------------------------- To call from the US dial 9:00 am Pacific US = home 011 34 923 271 082 12:00 noon Eastern US = cell 011 34 650 525 458 6:00 pm Spain -------------------------------------------------- -------------------------------------------------- Miguel Howard miguel@xxxxxxxxxxx c/Peña Primera 11-13 esc dcha 6B 37002 Salamanca España Spain -------------------------------------------------- telefono casa 923 27 10 82 movil 650 52 54 58 -------------------------------------------------- To call from the US dial 9:00 am Pacific US = home 011 34 923 271 082 12:00 noon Eastern US = cell 011 34 650 525 458 6:00 pm Spain --------------------------------------------------
