Created attachment 926155 [details]
gui installer screenshot, showing the advanced partitioning layout
Description of problem:
When I create empty mdadm-based software RAIDs or LVM Volume Groups outside of the GUI installer, I can't reuse them for system installation.
The reasoning behind this is to create a disk layout not supported by the GUI, like custom Physical Extent size of the LVM VG or various mdadm metadata (bitmap settings). All of these are pretty much standard (advanced) operations supported by the tools, with full metadata compatibility.
See the attached screenshot.
Version-Release number of selected component (if applicable):
(the version used for the official RHEL-7.0 DVD)
You should be able to do this. Create them, then use the circular arrow button to rescan the system. If that isn't working please include:
1. EXACT steps used to create these from the cmdline and actions taken in the GUI.
2. The logs from /tmp/*log attached here as *individual* text/plain attachments.
I removed the raid/vg from a shell within anaconda (alt+f2), zeroed the metadata and started again, from the same shell, meaning the commands should be fully reproducible without an external system.
# create the partitions used (make sure to use an empty disk,
# eg. all zeroes, otherwise leftover metadata may be detected)
$ sfdisk -L /dev/vda <<EOF
# partition table of /dev/vda
/dev/vda1 : start= 2048, size= 1048576, Id=83, bootable
/dev/vda2 : start= 1050624, size= 10485760, Id=83
/dev/vda3 : start= 11536384, size= 9435136, Id=8e
/dev/vda4 : start= 0, size= 0, Id= 0
Checking that no-one is using this disk right now ...
Disk /dev/vda: 20805 cylinders, 16 heads, 63 sectors/track
Units: cylinders of 516096 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/vda1 * 2+ 1042- 1041- 524288 83 Linux
/dev/vda2 1042+ 11444- 10403- 5242880 83 Linux
/dev/vda3 11444+ 20805- 9361- 4717568 8e Linux LVM
/dev/vda4 0 - 0 0 0 Empty
Units: sectors of 512 bytes, counting from 0
Device Boot Start End #sectors Id System
/dev/vda1 * 2048 1050623 1048576 83 Linux
/dev/vda2 1050624 11536383 10485760 83 Linux
/dev/vda3 11536384 20971519 9435136 8e Linux LVM
/dev/vda4 0 - 0 0 Empty
Successfully wrote the new partition table
Re-reading the partition table ...
If you created or changed a DOS partition, /dev/foo7, say, then use dd(1)
to zero the first 512 bytes: dd if=/dev/zero of=/dev/foo7 bs=512 count=1
$ ls -l /dev/vda*
brw-rw----. 1 root disk 252, 0 Aug 13 09:34 /dev/vda
brw-rw----. 1 root disk 252, 1 Aug 13 09:34 /dev/vda1
brw-rw----. 1 root disk 252, 2 Aug 13 09:34 /dev/vda2
brw-rw----. 1 root disk 252, 3 Aug 13 09:34 /dev/vda3
# create the raid, use 'far' layout with 2 copies, see md(4)
# for details
$ mdadm --create --metadata 1.2 --level 10 --raid-devices 2 --layout f2 /dev/md0 /dev/vda2 missing
mdadm: array /dev/md0 started.
# create the volume group, use large PE size
$ vgcreate -s 128M testvg /dev/vda3
Physical volume "/dev/vda3" successfully created
Volume group "testvg" successfully created
Then switch to the GUI installer (alt+f6), reload storage configuration, see Unknown/unusable devices for the raid/lvm, with only vda1 (standard partition) being reusable.
It seems that the installer tries to detect / use device on its own, based on the metadata, instead of re-using existing block devices available on the system. This would explain raid/lvm detection even when both were inactive/stopped.
Bug 1129300 mentions that a degraded raid is unsupported, which would invalidate the raid use case for the time being, but the LVM VG should have been detected/reusable.
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What makes you say the preexisting devices are unusable?
(In reply to David Lehman from comment #11)
> What makes you say the preexisting devices are unusable?
Please read comment #0 and see the attached screenshot (attachment 926155 [details]).
"Unusable" as in "can't be re-used for installation without prior removal".
I would expect the installer to be able to use the existing LVM VG (volume group) for creation of new LVs (logical volumes). In addition, I would also expect the installer to be able to format (create filesystem on) an existing raid block device (assemble the raid).
(In reply to Jiri Jaburek from comment #12)
> I would expect the installer to be able to use the existing LVM VG (volume
> group) for creation of new LVs (logical volumes). In addition, I would also
> expect the installer to be able to format (create filesystem on) an existing
> raid block device (assemble the raid).
You can. Just create a mountpoint, it will be added to one of the existing VGs with free space, and from there you can change which VG the mountpoint should ultimately be added to.
RHEL 7.1 removes some of the confusion by not showing empty volume groups as unknown devices.