[parted-devel] shrink partition and ext3 file-system on it from the beginning using parted

[Martin T]

Aren't there already plenty of partitioning tools like fdisk,
cfdisk(nice curses environment) or sfdisk(scriptable)? The downside of
Gparted is that it's not a CLI program, other that that it's very
useful in my opinion. For "sliding" the file-system it uses some sort
of internal algorithm according to log file:


move file system to the right  05:48:52    ( SUCCESS )

perform read-only test  01:54:58    ( SUCCESS )

using internal algorithm
read 611.40 GiB
finding optimal block size

read 16.00 MiB using a block size of 2.00 MiB  00:00:00    ( SUCCESS )

16.00 MiB of 16.00 MiB read
0.215304 seconds
read 16.00 MiB using a block size of 4.00 MiB  00:00:00    ( SUCCESS )

16.00 MiB of 16.00 MiB read
0.250469 seconds
read 16.00 MiB using a block size of 8.00 MiB  00:00:01    ( SUCCESS )

16.00 MiB of 16.00 MiB read
0.215766 seconds
read 16.00 MiB using a block size of 16.00 MiB  00:00:00    ( SUCCESS )

16.00 MiB of 16.00 MiB read
0.253064 seconds
optimal block size is 2.00 MiB
read 611.34 GiB using a block size of 2.00 MiB  01:54:57    ( SUCCESS )

611.34 GiB of 611.34 GiB read
611.40 GiB (656486170624 B) read
perform real move  03:53:54    ( SUCCESS )

using internal algorithm
copy 611.40 GiB
finding optimal block size

copy 16.00 MiB using a block size of 1.00 MiB  00:00:01    ( SUCCESS )

16.00 MiB of 16.00 MiB copied
0.988301 seconds
copy 16.00 MiB using a block size of 2.00 MiB  00:00:00    ( SUCCESS )

16.00 MiB of 16.00 MiB copied
0.53326 seconds
copy 16.00 MiB using a block size of 4.00 MiB  00:00:01    ( SUCCESS )

16.00 MiB of 16.00 MiB copied
0.598635 seconds
copy 16.00 MiB using a block size of 8.00 MiB  00:00:01    ( SUCCESS )

16.00 MiB of 16.00 MiB copied
0.530564 seconds
copy 16.00 MiB using a block size of 16.00 MiB  00:00:00    ( SUCCESS )

16.00 MiB of 16.00 MiB copied
0.522437 seconds
optimal block size is 16.00 MiB
copy 611.32 GiB using a block size of 16.00 MiB  03:53:51    ( SUCCESS )

611.32 GiB of 611.32 GiB copied
611.40 GiB (656486170624 B) copied


PS: thank you for this pv trick :)


Martin

Kuupäeval 25. aprill 2012 1:27 kirjutas Håkon Løvdal <hlovdal at gmail.com>:
> On 24 April 2012 21:28, Martin T <m4rtntns at gmail.com> wrote:
>> I was fairly sure that parted is able to handle such operations, but
>> for my surprise it's heading away from operations related to file
>> systems.. In case one can't use Gparted, I guess the best option is
>> to:
>
> I am not sure if this was supported, and the reason for removing
> file system code from parted was that it was not maintained and
> I think parts of it had known problems that were not fixed. So parted
> is consolidating on its core business, partition management, and
> then let file system specific programs do the file system operations.
> Since parted also is available as a library it is possible to combine
> partition management and file system operation in other programs,
> like Gparted.
>
>
>> 1) shrink the file system(resize2fs) and then partition(fdisk) towards
>> the beginning
>> 2) create a new partition(fdisk) and file system(mkfs.ext3) to the
>> space which was freed in the first step
>> 3) copy(cp -a) content of first file system to the second file
>> system(the one which was created in step 2)
>> 4) delete the first partition
>> 5) associate the new partition with the correct mount point in /etc/fstab
>>
>> Any other options/suggestions for shrinking the partition and
>> file-system in it starting from the beginning from the CLI?
>
> This sounds like a correct approach, although you can skip step 5
> if you use label or uuid instead of device file name to identify the partition.
>
> Also while "cp -a" makes identical copies of files, it will not preserve SELinux
> information, so using a tar[1] pipe to copy is probably preferable.
> If you pipe through pv[2] as well you get very nice progress information, e.g.
>
> (cd /mnt/source; tar cf - . ) | pv -s $(du -sb /mnt/source | awk
> '{print $1}') | (cd /mnt/target; tar xf -)
>
> [1]
> http://docs.fedoraproject.org/en-US/Fedora/13/html/SELinux_FAQ/index.html#id3037344
> [2]
> http://www.ivarch.com/programs/pv.shtml
>
> BR Håkon Løvdal