[linux-lvm] Is it considered safe to resize a mounted partition (root filesystem) with lvextend

Andy Smith andy at strugglers.net
Thu Nov 10 11:22:40 UTC 2016

Hi Kevin,

On Thu, Nov 10, 2016 at 09:12:58AM +0200, Kevin Wilson wrote:
> Is it safe to extend a mounted partition ?

Yes, if the tool you would use without LVM (e.g. resize2fs) is safe
for that. LVM just uses the appropriate tool, in your case
resize2fs, which can handle on-line resize.

> If I try it I get:
> "on-line resizing required" message, which I am not sure what it means.

It means that resize2fs has detected that the device is mounted and
so is doing an on-line resize. It is merely informational. That
message comes from resize2fs and so this is not really an LVM

As you can see…

> lvextend --size +20G --resizefs /dev/mapper/vg_paeiserver5-lv_my_partition
>   Extending logical volume lv_ubuntu to 34.00 GiB
>   Logical volume lv_ubuntu successfully resized

…from this point on the output comes from the resize2fs program.

> resize2fs 1.42.9 (4-Feb-2014)
> Filesystem at /dev/mapper/vg_paeiserver5-lv_my_partition is mounted on
> /; on-line resizing required
> old_desc_blocks = 1, new_desc_blocks = 3
> The filesystem on /dev/mapper/vg_paeiserver5-lv_my_partition is now
> 8912896 blocks long.


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