17.04 free -g is not showing swap space for btrfs filesystem

Bug #1656915 reported by bugproxy
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Release Notes for Ubuntu
Fix Released
Undecided
Dimitri John Ledkov
debian-installer (Ubuntu)
Opinion
Undecided
Taco Screen team

Bug Description

== Comment: #0 - PAVAMAN SUBRAMANIYAM - 2017-01-16 03:58:57 ==
---Problem Description---
free -g is not showing swap space for btrfs filesystem installed as Guided Partitioning of Ubuntu 17.04

---uname output---
Linux ltc-garri2 4.9.0-11-generic #12-Ubuntu SMP Mon Dec 12 16:16:45 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux

Machine Type = P8

---Steps to Reproduce---
Install a P8 8335-GTB Hardware with Ubuntu17.04 OS.
Then check if the swap space is shown using free command.

root@ltc-garri2:~# free -g
              total used free shared buff/cache available
Mem: 127 1 125 0 0 124
Swap: 0 0 0

I have selected Guided - use entire disk in Partition disks Menu while installing Ubuntu 17.04.
Then selected the Partition to modify its filesystem settings to btrfs journaling file system and created the same.

== Comment: #8 - Kevin W. Rudd - 2017-01-16 12:12:04 ==

Hello Canonical.

We had a couple of new bugs opened up recently (including this one) that are related to the 17.04 change to using swapfiles instead of swap partitions in certain cases. This is generating some confusion and questions.

? Do you have a current release note document for 17.04 that outlines this change and the various scenarios where a swap partition or volume might still be needed?

Related to the above question, it appears that btrfs needs a special mention for Zesty installs:

In the past, btrfs has been used for testing by simply changing the filesystem chosen as part of the "Guided partitioning" option. This will no longer work as a swap partition is not automatically created for this option, and btrfs does not currently support swapfiles:

https://btrfs.wiki.kernel.org/index.php/FAQ#Does_btrfs_support_swap_files.3F

An entry documenting the need for manual partitioning (including a swap partition) or recommending an LVM configuration for btrfs would probably be helpful in this case.

Revision history for this message
bugproxy (bugproxy) wrote : Example sosreport

Default Comment by Bridge

tags: added: architecture-ppc64le bugnameltc-150593 severity-high targetmilestone-inin1704
Changed in ubuntu:
assignee: nobody → Taco Screen team (taco-screen-team)
affects: ubuntu → debian-installer (Ubuntu)
Revision history for this message
Dimitri John Ledkov (xnox) wrote :

Correct, we have switched to using swapfiles by default.
Btrfs filesystem itself is not the default, and does not support swapfiles.
If you would like to have swap with btrfs rootfs, please use a custom partman-auto preseed recipy with swap.

Changed in debian-installer (Ubuntu):
status: New → Opinion
Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2017-01-16 13:48 EDT-------
Thanks xnox.

The reason for the submitter's mirror request was to get this recommendation a bit more formally documented. From an earlier comment in this bug:

(In reply to comment #4)
> We had already discussed about the same and we wanted to have the Ubuntu
> Release documents correctly mentioning the same about creating swap
> partitions.
>
> So, I had opened this bug since Ubuntu has claimed as below:
> =====================================================
> Starting from 17.04 Zesty Zapus release, instead of creating swap
> partitions, swapfiles will be used by default for non-lvm based
> installations.
>
> Secondly, the sizing of swapfiles is very different. It is no more than 5%
> of free disk space or 2GiB, whichever is lower.
>
> Ref link: http://blog.surgut.co.uk/
>
> So, wanted to make sure that Ubuntu updates in its Release notes that
> swapfiles will not be used in case of BTRFS by default.

Thanks.

bugproxy (bugproxy)
tags: added: severity-medium
removed: severity-high
Revision history for this message
Dimitri John Ledkov (xnox) wrote :

with 128G of RAM one should not need swap at all.

Changed in ubuntu-release-notes:
assignee: nobody → Dimitri John Ledkov (xnox)
status: New → Confirmed
Revision history for this message
Dimitri John Ledkov (xnox) wrote :

Adding release notes task, such that it does not get lost.

Revision history for this message
bugproxy (bugproxy) wrote :

------- Comment From <email address hidden> 2017-04-12 02:42 EDT-------
Are the release notes updated in the Ubuntu 17.04 official release.
This bug related information should be updated into the Releases notes.

Revision history for this message
bugproxy (bugproxy) wrote :

------- Comment From <email address hidden> 2017-05-01 12:39 EDT-------
(In reply to comment #18)
> Are the release notes updated in the Ubuntu 17.04 official release.
> This bug related information should be updated into the Releases notes.

Hi Dimitri.

It looks like this may have been lost after all. Getting a note added to the "Known issues" section of the release notes documenting the need for a swap partition for a btrfs configuration would allow us to close this bug out.

Thanks.

Revision history for this message
Dimitri John Ledkov (xnox) wrote :
Changed in ubuntu-release-notes:
status: Confirmed → Fix Released
Revision history for this message
bugproxy (bugproxy) wrote :

------- Comment From <email address hidden> 2017-05-02 11:29 EDT-------
(In reply to comment #20)
> Added at https://wiki.ubuntu.com/ZestyZapus/ReleaseNotes#Installation

Perfect. Thanks much. I think we can close this one down now.

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