[NTLUG:Discuss] Resizing Linux partitions

[Robert Pearson]

On 6/18/07, Robert Citek <robert.citek at gmail.com> wrote:
> On 06/15/2007 07:32 PM, Leroy Tennison wrote:
> > No big deal since is was a test partition anyway, just some time
> > wasted.  However, I am now very curious as to how you are supposed to go
> > about resizing both ext3 and reiserfs partitions.  Anyone have good
> > success with this using any non-commercial program?
>
> Just to clarify, there is a difference between a filesystem and a
> partition.  Partitions contain filesystems.  Put another way, a
> filesystem resides inside a partition.  That distinction is important
> because you can resize a filesystem without resizing the partition
> containing it and vice-versa.  That is, you can shrink a filesystem so
> that it is much smaller than the partition containing it.  Also, you can
> expand a partition without expanding the filesystem.  Most filesystem
> resizing tools prevent the obvious problem of expanding a filesystem
> beyond the partition boundary.  However, most partitioning tools do not
> prevent the problem of shrinking a partition below the filesystem size
> (e.g. fdisk).
>
> Filesystem resizers:
>  - ext2/3 : resize2fs
>  - ntfs : ntfsresize
>  - reiserfs: resize_reiserfs
>
> Partition resizers (any disk partitioning tool):
>  - fdisk
>  - parted
>
> Tools that do both:
>  - qtparted (gui)
>  - gparted (gui)
>
> The tools that do both use some combination of the filesystem and
> partitioning tools behind the scenes, giving the appearance of "resizing
> a linux partition."
>
> BTW, you can play with resizing a filesystem using just files.  For
> example, here's how to create an ext3 filesystem within a file, shrink
> the filesystem without shrinking the file, grow the filesystem, grow the
> file without growing the filesystem, and grow the filesystem:
>
> $ dd if=/dev/zero of=ext3.img bs=1M count=10
>
> $ ls -la --si ext3.img
> -rw-r--r-- 1 rwcitek rwcitek 11M 2007-06-18 12:20 ext3.img
>
> $ mkfs.ext3 -q ext3.img
> ext3.img is not a block special device.
> Proceed anyway? (y,n) y
>
> $ e2fsck -n ext3.img
> e2fsck 1.38 (30-Jun-2005)
> ext3.img: clean, 11/2560 files, 1372/10240 blocks
>
> $ resize2fs -f ext3.img  1372
> resize2fs 1.38 (30-Jun-2005)
> Resizing the filesystem on ext3.img to 1372 (1k) blocks.
> The filesystem on ext3.img is now 1372 blocks long.
>
> $ e2fsck -n ext3.img
> e2fsck 1.38 (30-Jun-2005)
> ext3.img: clean, 11/1280 files, 1208/1372 blocks
>
> $ resize2fs -f ext3.img
> resize2fs 1.38 (30-Jun-2005)
> Resizing the filesystem on ext3.img to 10240 (1k) blocks.
> The filesystem on ext3.img is now 10240 blocks long.
>
> $ e2fsck -n ext3.img
> e2fsck 1.38 (30-Jun-2005)
> ext3.img: clean, 11/2560 files, 1372/10240 blocks
>
> $ dd if=/dev/zero bs=1M count=10 >> ext3.img
> 10+0 records in
> 10+0 records out
> 10485760 bytes (10 MB) copied, 0.037845 seconds, 277 MB/s
>
> $ ls -la --si ext3.img
> -rw-r--r-- 1 rwcitek rwcitek 21M 2007-06-18 12:23 ext3.img
>
> $ resize2fs -f ext3.img
> resize2fs 1.38 (30-Jun-2005)
> Resizing the filesystem on ext3.img to 20480 (1k) blocks.
> The filesystem on ext3.img is now 20480 blocks long.
>
> $ e2fsck -n ext3.img
> e2fsck 1.38 (30-Jun-2005)
> ext3.img: clean, 11/3840 files, 1534/20480 blocks
>
> HTH.
>
> Regards,
> - Robert

Thanks. This is great.
It cleared up a lot of confusion for me.
Now I need some help understanding the Volume Manager (LVM),
partitions and file systems.
The goal is to be able to resize (shrink or grow) using the Volume Manager.
The reading indicates this pretty much makes you file system and
partition independent.
So far I have destroyed everything I have tried using all three of these.
All help is appreciated.