openstack-api-site

Size units are ambiguous in blockstorage createVolume API documentation

Bug #1456631 reported by Richard Wall
10
This bug affects 2 people
Affects Status Importance Assigned to Milestone
openstack-api-site
Fix Released
Medium
Diane Fleming
openstack-api-site liberty
openstack-manuals
Fix Released
Medium
Diane Fleming
openstack-manuals liberty

Bug Description

The documentation says size in GBs
 * http://developer.openstack.org/api-ref-blockstorage-v2.html#createVolume

```
The size of the volume, in GBs.
```

But the implementations (that I've looked at) seem to interpret the supplied size as GiB

 * http://bazaar.launchpad.net/~cinder-coresec/cinder/github/view/head:/cinder/volume/flows/api/create_volume.py#L35

```
GB = units.Gi
```

 * http://git.openstack.org/cgit/openstack/oslo.utils/tree/oslo_utils/units.py#n23

```
Gi = 1024 ** 3
```

Eg

 * The LVM driver appends `g` to the size

http://bazaar.launchpad.net/~cinder-coresec/cinder/github/view/head:/cinder/volume/drivers/lvm.py#L101

Which is interpreted by LVM as GiB...according to the `lvs` documentation

http://linux.die.net/man/8/lvs

```
--units hHbBsSkKmMgGtTpPeE
    All sizes are output in these units: (h)uman-readable, (b)ytes, (s)ectors, (k)ilobytes, (m)egabytes, (g)igabytes, (t)erabytes, (p)etabytes, (e)xabytes. Capitalise to use multiples of 1000 (S.I.) instead of 1024. Can also specify custom units e.g. --units 3M
```

There is a related LVM documentation bug here:
 * https://bugs.launchpad.net/ubuntu/+source/lvm2/+bug/1083680

This is causing failures in our tests against Rackspace OpenStack, because we convert our `Byte` sizes to `GB` rather than `GiB`

 * https://github.com/ClusterHQ/flocker/pull/1419#issuecomment-103441866

Diane Fleming (diane-fleming)
Changed in openstack-api-site:
assignee: nobody → Diane Fleming (diane-fleming)
importance: Undecided → Medium
status: New → Confirmed
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix proposed to api-site (master)

Fix proposed to branch: master
Review: https://review.openstack.org/184405

Changed in openstack-api-site:
status: Confirmed → In Progress
Revision history for this message
Diane Fleming (diane-fleming) wrote :

Also affects http://docs.openstack.org/user-guide/ and http://docs.openstack.org/cli-reference/content/cinderclient_commands.html.

Changed in openstack-manuals:
assignee: nobody → Diane Fleming (diane-fleming)
importance: Undecided → Medium
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix proposed to openstack-manuals (master)

Fix proposed to branch: master
Review: https://review.openstack.org/184406

Changed in openstack-manuals:
status: New → In Progress
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix merged to api-site (master)

Reviewed: https://review.openstack.org/184405
Committed: https://git.openstack.org/cgit/openstack/api-site/commit/?id=b32caadc5dc500b04ee19fe9572a9205ec3ab903
Submitter: Jenkins
Branch: master

commit b32caadc5dc500b04ee19fe9572a9205ec3ab903
Author: Diane Fleming <email address hidden>
Date: Tue May 19 21:34:33 2015 -0500

    Update volume size from GB to GiB

    Change-Id: I090b9a3d46511061811bdaffda219a662497b61f
    Partial-Bug: #1456631

OpenStack Infra (hudson-openstack)
Changed in openstack-manuals:
assignee: Diane Fleming (diane-fleming) → Andreas Jaeger (jaegerandi)
Andreas Jaeger (jaegerandi)
Changed in openstack-manuals:
assignee: Andreas Jaeger (jaegerandi) → Diane Fleming (diane-fleming)
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix merged to openstack-manuals (master)

Reviewed: https://review.openstack.org/184406
Committed: https://git.openstack.org/cgit/openstack/openstack-manuals/commit/?id=9f3d13715a30746a495ee4abaf52c0854e9ecae3
Submitter: Jenkins
Branch: master

commit 9f3d13715a30746a495ee4abaf52c0854e9ecae3
Author: Diane Fleming <email address hidden>
Date: Tue May 19 21:51:46 2015 -0500

    Change GB to GiB for volume creation

    Change-Id: Ice7dd127a12ce453454808043af6ba34996e3a21
    Closes-Bug: #1456631

Changed in openstack-manuals:
status: In Progress → Fix Released
Revision history for this message
Richard Wall (richardw) wrote :

Another complication is that some cinder drivers appear to over allocate when the storage backend is only capable of allocating space in fixed intervals of > 1GiB.

For example,

After requesting a 100 GiB volume via `nova volume-create 100` and attaching it to my instance, `lsblk` now reports

```
[centos@clusterhq-flocker-buildslave ~]$ sudo lsblk --bytes --output SIZE /dev/vdb
        SIZE
111669149696

```

Which is exactly 104 GiB

```
In [12]: Byte(111669149696).to_GiB()
Out[12]: GiB(104.0)
```

Which makes me think that GB vs GiB is less important than I thought.
Telling people GB and actually creating GiB (or more) is just another form of over allocation, right?

One complication is that if I now fill this block device I might to be able to move the data to another 100 GiB cinder block device on another cinder platform....but that platform may have a different allocation interval and its 100 GiB volume may not have room.

Diane Fleming (diane-fleming)
Changed in openstack-api-site:
milestone: none → liberty
Changed in openstack-manuals:
milestone: none → liberty
Changed in openstack-api-site:
status: In Progress → Fix Released
Revision history for this message
OpenStack Infra (hudson-openstack) wrote : Fix included in openstack/openstack-manuals 15.0.0

This issue was fixed in the openstack/openstack-manuals 15.0.0 release.

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