Custom partitioner creates extended partition incorrectly

[Krzysztof Lichota]

Kubuntu dapper live cd version: RC1

Scenario:
1. Disk with 1 partition hda1 (NTFS) and free space behind it.
2. Run Ubiquity, select custom partitioning.
3. Create extended partition spanning the whole free space.
4. Add swap partition as logical partition on extended partition.
5. Add root partition as logical partition on extended partition. It should _not_ fill whole extended partition size, leaving some space for other logical partitions to be added later.
6. Run installation.
7. Partitions created do not reflect the choices - extended partition created spans only to hold swap and root partition, the remaining free space does not belong to extended partition. This means user can create only primary partitions on this drive (which is limited), no matter how much free space is there.

[Krzysztof Lichota (krzysiek-launchpad-ubuntu-com)]

syslog (partial, as I have interrupted installation after checking that partitioning is bad)

[Krzysztof Lichota (krzysiek-launchpad-ubuntu-com)]

partman log (partial, as I have interrupted installation after checking that partitioning is bad)

[Krzysztof Lichota (krzysiek-launchpad-ubuntu-com)]

This is screenshot of qtparted with partition layout. I have made it during installation, after partitioning was performed.

[Colin Watson (cjwatson)]

partman always minimises the extended partition. I don't really see that this is a big problem, though, as decent parted-based partition managers ought to resize the extended partition on-demand to cope with adding more logical partitions. It's not as if changing the size of an extended partition is difficult.

[Colin Watson (cjwatson)]

For reference, this (from partman-base/parted_server.c) is the libparted code that a partition editor can use to grow the extended partition if necessary, assuming a PedDisk *disk:

        PedPartition *extended;
        extended = ped_disk_extended_partition(disk);
        ped_disk_maximize_partition(disk, extended,
                                    ped_constraint_any(disk->dev));

Not rocket science. :-)

[Krzysztof Lichota (krzysiek-launchpad-ubuntu-com)]

Yes, but partitioner should obey explicit user request. If user chooses to create 15 GB extended partition, partitioner should create 15 GB extended partition, not 5 GB.

It could also spoil automatic partitioning tools, for example for OEM installs.

[seisen1 (seisen-deactivatedaccount-deactivatedaccount)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. You reported this bug a while ago and there hasn't been any activity in it recently. We were wondering is this still an issue for you? Can you try with latest Ubuntu release? Thanks in advance.

[Colin Watson (cjwatson)]

This is fixed, after a fashion. The partitioner no longer offers the opportunity to explicitly create an extended partition; you can create primary or logical partitions, and it will do whatever it needs to do in terms of extended partitions. Thus there is no longer a conflict between an explicit user request and what the partitioner does.

I don't plan to restore the ability to explicitly lay out extended partitions. It isn't necessary in an installer context, and as I noted it is trivial to resize extended partitions provided that there is some adjacent unpartitioned space. I have never heard of a real case where this caused a problem for automatic or OEM installations, and I've dealt with a lot of those.

[psl (slansky)]

I met this issue during install of Ubuntu 8.04.1 too. I don't like it, it creates trouble for other installations, for adding new partitions, etc. I was not prepared for this behavior and I was surprised. I think I see some reasons why extended partition is kept at minimum size but I think this should be only one option; default. User should be able to configure partitioner to create extended partition with minimum or maximum size. From my point of view, partitioner should ask user about size of extended partition (minimal maximal, custom size).