I experimented a bit further, and may have found an error in mdadm.
Again, this was my setup:
- OS Fedora 14 fully updated, running in VirtualBox
- mdadm version 3.1.4, fully updated (as of today) from the git repo
- Five virtual disks, 1 GB each, to use
I created two raid sets out of one ddf container:
mdadm -C /dev/md127 -l container -e ddf -n 5 /dev/sd[b-f]
mdadm -C /dev/md1 -l 1 -n 2 /dev/md127
mdadm -C /dev/md2 -l 2 -n 3 /dev/md127
Disks sdb and sdc were used for the RAID 1 set, disks sdd, sde, sdf were
used for the RAID 5 set.
All were fine and the command mdadm -E /dev/md127 showed all disks
active/Online
Now I failed one of the disks of md1:
mdadm -f /dev/md1 /dev/sdb
Indeed, looking at /proc/mdstat I saw the disk marked failed [F] before
it was automatically removed within a second (a bit weird).
Now comes the weirdest part, mdadm -E /dev/md127 did show one disk as
"active/Online, Failed" but this was disk sdd
which is part of the other RAID set!
When I removed the correct disk, which can only be done from the container:
mdadm -r /dev/md127 /dev/sdb
the command mdadm -E /dev/md127 showed the 5 disks, the entry for sdb
didn't had a device but was still
"active/Online" and sdd was marked Failed:
Physical Disks : 5
Number RefNo Size Device
Type/State
0 d8a4179c
1015808K active/Online
1 5d58f191 1015808K /dev/sdc
active/Online
2 267b2f97 1015808K /dev/sdd
active/Online. Failed
3 3e34307b 1015808K /dev/sde
active/Online
4 6a4fc28f 1015808K /dev/sdf
active/Online
When I try to mark sdd as failed, mdadm tells me that it did it, but
/proc/mdstat doesn't show the disk as failed,
everything is still running. I also am not able to remove it, as it is
in use (obviously).
So it looks like there are some errors in here.
Albert
On 02/19/11 12:13 PM, Albert Pauw wrote:
I have dabbed a bit with the standard raid1/raid5 sets and am just
diving into this whole ddf container stuff,
and see how I can fail, remove and add a disk.
Here is what I have, Fedora 14, five 1GB Sata disks (they are virtual
disks under VirtualBox but it all seems
to work well under the standard raid stuff. For mdadm I am using the
latest git version, with version nr 3.1.4.
I created a ddf container:
mdadm -C /dev/md/container -e ddf -l container -n 5 /dev/sd[b-f]
I now create a raid 5 set in this container:
mdadm -C /dev/md1 -l raid5 -n 5 /dev/md/container
This all seems to work, I also noticed that after a stop and start of
both the container and the raidset,
the container has been renamed to /dev/md/ddf0 which points to
/dev/md127.
I now fail one disk in the raidset:
mdadm -f /dev/md1 /dev/sdc
I noticed that it is removed from the md1 raidset, and marked
online,failed in the container. So far so
good. When I now stop the md1 array and start it again, it will be
back again with all 5 disks, clean, no failure
although in the container the disk is marked failed. I then remove it
from the container:
mdadm -r /dev/md127 /dev/sdc
I clean the disk with mdadm --zero-superblock /dev/sdc and add it again.
But how do I add this disk again to the md1 raidset?
I see in the container that /dev/sdc is back, with status
"active/Online, Failed" and a new disk is added
with no device file and status "Global-Spare/Online".
I am confused now.
So my question: how do I replace a faulty disk in a raidset, which is
in a ddf container?
Thanks and bare with me, I am relatively new to all this.
Albert
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