Resize ext3 Partition

[Jeff Vian]

On Sat, 2005-01-22 at 21:23 -0800, Shane Archer wrote:
> At 05:04 PM 1/22/2005, you wrote:
> 
> >If / is that large, what subdirectory is the biggest?  Is /home or /opt
> >in / and not on a separate partition?  I would guess you have a LOT of
> >downloaded stuff there that is bloating / unreasonably large.
> >
> >You can easily do a backup of the bulk of the stuff there to get it out
> >of the way.  Maybe put it off onto CDs to recover the space. Then after
> >reducing the space required, the actual OS part of / should be about 3 -
> >5 GB instead of the current 38GB.  That could be moved to a new
> >partition in its entirety and by making a small change in grub.conf and
> >fstab you could boot to the new partiton for your system.
> >
> >Once the old / partition is not in use you would be free to do whatever
> >was needed to resize it.
> 
> This sounds like the most viable option yet, although I am not familiar 
> with the changes I'd have to make to fstab and grub.conf.
> 

If you do not relocate / you would not need to modify grub.conf.  I
would rather relocate /home than try and relocate / if I were doing it.

> Suppose that I just want to move something like /home or /var to another 
> partition. What changes would I need to make to fstab to make it happen?
> 

1. create the new partition and format
2. mount the new filesystem somewhere. (mount /dev/hdXY /mnt)
3. copy all the files from old to new 
   cd /home
   cp -a <username> /mnt

Now it gets tricky, because once the filesystem is mounted you cannot
remove the old files from /home

4. logout, and log back in as root (you need to not have any files in
the /home being used)
5. edit /etc/fstab and create a line to mount the new filesystem at the
chosen location
(/dev/hdXY   /home    ext3    defaults   1 2) or equivalent.
6. delete all the files in the original /home (rm -rf /home/username
7. mount the mew /home 
   mount -a
8. verify it mounted properly 
   mount
9. logout and log back in as your regular user and you are done.

Note that if you have more than one user in /home, the cp command in
step 3 and the rm command in step 6 will be required for each user.

Also note that it will be a good idea to use the du command to confirm
what size partition is required before you create it.  (du -s /home)



> The main reason for all of this is because I'd like to copy a 6.5GB 
> database from one of my web servers (hosted elsewhere) to my local machine 
> for testing, and I need to create space for it. If I could just move /var 
> to another partition, that would solve my problem (and hopefully I'd learn 
> more in the process).
> 

Although moving /var would work, it is a system part of the tree and is
usually much smaller than /home.  It also would be tricky to move
without breaking the system (moving is similar to the example above
for /home, but it would require booting to rescue mode to do the part
involving deleting of the old files and getting the new /var mounted)

To see which part of the tree would give you the best benefit and the
space requirements, a simple "du -s /*" will give you an output that
will tell you which parts of the tree are heavy and which are not.  On
mine, /home has at least 4 times the space requirements of any other
branch (in fact it is that much larger than all other branches
combined).  My default install I use (except for /home) fits easily
within a 10GB partition and has lots of room to grow.  For your 6+ GB
database you may need up to 15 or 20GB to allow extra room but not
likely more.

I would suspect you will see similar results in space requirements and
there are advantages to having /home in it's own partition.  Mostly, if
a new install is required, /home does not need to be formated and thus
your customized data and directory structure does not get wiped out.
 


> Thanks,
> 
> Shane 
>