Jonathan Tripathy wrote:
>Would resize2fs allow you to
"over-commit" ? I'd imagine that if the
>LV size was smaller than
expected, wouldn't it throw an error?
Indeed it does :
# lvm
lvcreate -n test -L 1G vg0
Logical volume "test" created
#
mkfs -t ext3 /dev/vg0/test
...
# fsck -f /dev/vg0/test
...
#
resize2fs /dev/vg0/test 2G
resize2fs 1.41.3 (12-Oct-2008)
The containing
partition (or device) is only 262144 (4k) blocks.
You requested a new size of
524288 blocks.
So there's no problem resizing the
filesystem.
What that won't help with is if you resize the
underlying volume to
be too small for the filesystem :
# lvm lvcreate
-n test -L 3G vg0
Logical volume "test" created
# mkfs -t
ext3 /dev/vg0/test
...
# fsck -f /dev/vg0/test
...
# resize2fs
/dev/vg0/test 2G
resize2fs 1.41.3 (12-Oct-2008)
Resizing the filesystem on
/dev/vg0/test to 524288 (4k) blocks.
The filesystem on /dev/vg0/test is now
524288 blocks long.
# lvm lvresize -L 1G /dev/vg0/test
WARNING: Reducing active logical volume to 1.00 GB
THIS MAY
DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce test? [y/n]:
y
Reducing logical volume test to 1.00 GB
Logical volume test successfully resized
# fsck -f /dev/vg0/test
fsck
1.41.3 (12-Oct-2008)
e2fsck 1.41.3 (12-Oct-2008)
Superblock has an invalid
ext3 journal (inode 8).
Clear<y>? no
fsck.ext3: Illegal inode
number while checking ext3 journal for /dev/vg0/test
To prevent
that, LVM would need to know about what might be in the
volume and prompt you
accordingly - but then it would lose that
decoupling between storage volumes
and filesystems.
Ie, if LVM "knew about" ext2/3 (and all the other)
filesystems, then
it could check the contents of the volume and ask you if
you were
sure you wanted to screw up your data. It would
significantly
increase the complexity of LVM to be able to do that
though.
-----------------------------------------------------------------------------------------------------------
Ah right, so this issues only really occurs when downsizing a
disk then? When upsizing (as mentioned in my first post), there isn't an issue,
as resize2fs would have thrown an erro, correct?
Also, on a slightly off-top note, I made a mistake: I dd'ed an image file
over to a non-exsistent LV. However, dd created a new file in /dev/vg0
!! Is this really bad? Could I have currupted some of the LVs? Or is it safe to
just remove the new file using rm?
Thanks
