Ext2online

[David D. Hagood]

Justin Conover wrote:
> On 7/7/05, Ivan Gyurdiev <ivg2 at cornell.edu> wrote:
>> What does this mean?
>> 
>> [root at cobra ~]# /usr/sbin/ext2online /dev/cobra/root
>> ext2online v1.1.18 - 2001/03/18 for EXT2FS 0.5b
>> ext2online: group 0, block 2 not reserved
>> 
>> ext2online: unable to resize /dev/mapper/cobra-root
>> 
> Did you increase the size first?
> 
> lvextend -L+NG /dev/vg/lv
> 

My experience is that when you get the "block N not reserved" message it 
is because you are attempting to increase the size of the filesystem 
beyond what can be done online.

An EXT[2|3] filesystem, when created, has a hard limit on the size to 
which it can grow while mounted - to grow beyond this size requires the 
file system to be unmounted so that additional data structures can be 
created within it. I believe the rule of thumb is that you can double 
the size of the file system from what it was originally while it is 
mounted, but you cannot go beyond that without unmounting it and 
extending it.

XFS does not have this restriction, and IIRC neither does ReiserFS.

So, the upshot is that the file system will have to be unmounted and 
extended. If this is the rootfs then this will have to be done from a 
rescue disk or from the initrd (what I have done is to create an initrd 
that extends the partition to the maximum size of the partition it is 
in, and then I can simply invoke that initrd when needed.)