On 06/22/2014 02:28 PM, Ljubomir Ljubojevic wrote:
On 06/22/2014 10:15 AM, John R Pierce wrote:
so, I installed a c6 system offsite today, had to do it in a hurry. box has 2 disks meant to be mirrored... I couldn't figure out how to get anaconda to build a LVM root on a mirror, so I ended up just installing a /boot and vg_system on sda and raid it later.
every howto I find for linux says to half-raid the OTHER disk, COPY everything to it, then boot from it and wipe the first disk and then bond it as a mirror of the 2nd. Thats kind of ugly.
in solaris, you can tell it that your existing partition is half of a mirror, update /etc/vfstab, then reboot, and then join a mirror to it. this seems much cleaner to me than copying everything.
I tried to do this the solaris way, and at the first step, am told...
# mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sda2 missing mdadm: cannot open /dev/sda2: Device or resource busy/dev/sda2 contains the LVM root vg...
so... I'm thinking I''ll boot a rescue system from usb, create the half mirror, then reboot to the incomplete raid and add mirror /dev/sdb2
will the VG be found on /dev/md0 instead of on /dev/sda2 ? if so, is there any other reason this won't work?
This is a best RAID tutorial I saw so far, and I made it better and safer (commands by just copying will fail due to /dev/sdx naming): https://www.facebook.com/notes/centos/software-raid-on-rhel-6/10151254589767...
If you create just a RAID1 then you can get away with 1 failed device. I do not think RAID10 will be accepted with just one device + one failed.
There might be option to just change the type of partition on existing HDD and write metadata with mdraid command, joining it to some existing raid device, but I never tried it and I would not attempt it on important hdd's.
And here are commands for fast partition + RAID1 + RAID10 creation:
https://www.facebook.com/notes/centos/creating-partitions-for-raid/101517641...