Am Mittwoch, 4. Januar 2012, 22:45:45 schrieb Jeff Cranmer: > On Thu, 2012-01-05 at 04:01 +0100, Volker Armin Hemmann wrote: > > the short one: > > > > partition one disk with (c)fdisk. Use sfdisk to transfer the partition > > scheme to the other disks. > > > > run mdadm --create /dev/md0 level=whatever you want --raid- > > devices=thenumberofdevices /dev/sdXY /dev/sdZY ... > > > > mdadm --detail --scan >> /etc/mdadm.conf > > > > done > > OK, but there is active data on the disks, so I don't want to partition > them. They should already partitioned, and running fdisk will erase the > data.
first rule: always mount a scratch monkey In your case: always backup data. There is a way to preserve the data on one disk, create a raid5 with one disk missing, then copying the data onto the raid and add the disk. But that is high risk stuff. > > If I run mdadm --create /dev/md0 level=5 > --raid-devices=3 /dev/sdb /dev/sdc /dev/sdd, will that erase data > already on the disks? > > Prior to running this command, there is no /dev/md entry. Is this > correct? yes. You might have to create the nodes with mknod - my memory is sketchy there. > Looking further by using fdisk, it appears that sdc has a linux > partition on sdc1 starting at sector 34, and a GPT partition of size 0+ > at /dev/sdc4, sector 0. Nothing else is on that disk (no sdc2 or sdc3). > > sdd and sdb report invalid partition table flags and do not appear to > have active partitions. Does this make sense? if you used fakeraid before, yes. But that means: without the original fakeraid everything on that disks is inaccessible... and you need to partition them. > > Is it possible that I ordered the disks incorrectly when I installed > them, and by simply swapping disks b and c at the raid I can get things > to start making sense? Is there an order to a set of RAID5 disks? I > thought any two of three RAID5 disks could be recovered, regardless of > which one dies? no. First, the order of the disks is irrelevant, but the most important thing: with Raid5 ONE disk out of an array might fail. No matter how many disks - two fail and everything is lost. > > > there is a reason why I never ever touch genkernel. > > > > you should forget that crap. You don't need to copy around anything. If > > your root is not on some fancy setup, you don't need initramfs. > > > > Just make a nice kernel, put it in /boot. Done. > > OK. The OS disk is non-RAID (120GB SSD), so I don't need any fancy > options in my kernel. All the domdadm and dodmraid stuff is needed just > when your OS disk is raided. Correct? yes -- #163933
