Thanks Ionut for this suggestion.
You are right, it works if we reassemble the array from a Live CD and then
only shrink with --grow --size, thanks for the tip.
However, this seems to show that there is a bug in the way mdadm handles
this --grow --size, because in my procedure I was first unmounting the
array, thus the command should have been worked.
It is like if mdadm thinks that the array is still mounted even if it is not
and no files are accessed anymore. Also that is strange because when I mount
and unmount the array from the LiveCD, the grow command still work, whereas
when trying from the machine's OS where the array was created, it doesn't
work.
Can someone else confirm this bug and would it be possible to solve it?
Thanks,
Daniel
I had this problems too...the fix i have found was to use a Live CD,
rebuild array and then shrink...but maybe someone have a better idea.
On Tue, Jan 15, 2013 at 11:09 PM, dan1 <dan1@xxxxxxxxxxxx> wrote:
Hi,
I am trying to shrink an md partition to lower its size but that fails
with
an error message.
My context is the following:
/dev/md2 has 3 partitions: /dev/sdb3; /dev/sdc3; /dev/sdd3
The array is 480 Gbytes big (only 30 Gbytes used).
I want to resize it to 100Gbytes (hosting company only allows that size).
Following a procedure, I first resize the partition to 70Gbytes to let
some
space:
umount /dev/md2
e2fsck /dev/md2
resize2fs /dev/md2 70G
Then, I disable the bitmap:
mdadm --grow /dev/md2 --bitmap none
And I shrink the array to 100Gbytes (201x512x1024):
mdadm --grow /dev/md2 --size=105381888
Doing this, it produces the following error message:
mdadm: Cannot set size on array members.
mdadm: Cannot set device size for /dev/md2: Device or resource busy
If I look at the messages with "dmesg | tail" there is no error message
due
to that manipulation.
Some things to check:
1. No rebuild is in progress (with cat /proc/mdstat): OK
2. The array is unmounted: OK
3. The proble doesn't come from the bitmap as it has been disabled before.
OK
4. Opened files related to the md2 device are the following:
lsof | grep md2
md2_raid1 403 root cwd DIR 9,91 4096 2 /
md2_raid1 403 root rtd DIR 9,91 4096 2 /
md2_raid1 403 root txt unknown /
proc/403/exe
I don't know if this is ok or not but I assume it is fine as I didn't
mount
the array and didn't put any file on it in this session.
The versions of my system are the following:
Linux CentOS 6.3
mdadm V3.2.3
Thanks for any help.
Daniel
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Best regards,
Ionut
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