Bug 1439386 - [Docs] Document support for device aliases for OSDs
Summary: [Docs] Document support for device aliases for OSDs
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Red Hat OpenStack
Classification: Red Hat
Component: documentation
Version: 11.0 (Ocata)
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
: ---
Assignee: RHOS Documentation Team
QA Contact: RHOS Documentation Team
John Fulton
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-04-05 21:24 UTC by Don Domingo
Modified: 2018-02-21 04:33 UTC (History)
20 users (show)

Fixed In Version:
Doc Type: Enhancement
Doc Text:
Clone Of: 1232958
Environment:
Last Closed: 2018-02-21 04:33:37 UTC
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Launchpad 1677605 0 None None None 2017-04-05 21:25:41 UTC
OpenStack gerrit 451826 0 None None None 2017-04-05 21:26:55 UTC

Comment 1 Giulio Fidente 2017-04-05 22:21:02 UTC
Note that the patch allows for use of any alias built by udev and pointing to the disk, including: by-id, by-partuuid, by-path, by-uuid so other examples could be the wwn or the disk id:

/dev/disk/by-id/wwn-0x5000c5004531dc00
/dev/disk/by-id/ata-ST320LT007-9ZV142_W0Q2WNBM

Comment 2 Ben England 2017-04-05 22:48:37 UTC
True, but unlike by-id, by-uuid etc, /dev/disk/by-path can actually be the same across a set of similarly configured nodes, provided that the storage controller is in the same slot for all of them.  That's important because if you are deploying 100 nodes with 10 OSDs each, you will not want to have to construct the YAML for 1000 /dev/disk/by-id device pathnames, but you might be able to just reference 10 /dev/disk/by-path device pathnames.   For example, if you purchase a set of nodes at the same time, chances are you will see this level of consistency (but not always).  

That's partly why I filed this introspection problem report on Ironic:

https://bugs.launchpad.net/ironic/+bug/1679726

However, you can't always expect this level of consistency in /dev/disk/by-path device names across nodes, which is why I filed bzs 1438590 and 1438572 .

Should introspection be getting any additional information about the device that might be useful in constructing the Ceph OSD map?

You are correct that we can't document use of /dev/disk/by-path until we know the fix [1] is in RHOSP.

A good writeup on device naming is at: 

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/persistent_naming.html

Comment 3 Giulio Fidente 2017-04-06 10:26:50 UTC
hi Ben, I understand the reason of a 'property' based filter to select the disks, which you're proposing in BZ #1438590, I like that idea a lot and hopefully we get it implemented soon!

This BZ is about the recently added support for device aliases and the reason why I think it might be useful documenting more alias types and not only by-path is that wwn and serial of the disks don't change across reboots, while sdX references could.

Comment 4 Lucy Bopf 2017-07-27 02:15:15 UTC
Clearing target release pending docs triage.

Comment 5 Lucy Bopf 2017-07-31 04:54:01 UTC
(In reply to Giulio Fidente from comment #3)
> hi Ben, I understand the reason of a 'property' based filter to select the
> disks, which you're proposing in BZ #1438590, I like that idea a lot and
> hopefully we get it implemented soon!
> 
> This BZ is about the recently added support for device aliases and the
> reason why I think it might be useful documenting more alias types and not
> only by-path is that wwn and serial of the disks don't change across
> reboots, while sdX references could.

Giulio, is there a downstream RFE BZ for the device alias support? I can only see references to upstream patches, and I'd like to confirm which release this belongs to.

Comment 6 Giulio Fidente 2017-08-07 09:46:45 UTC
This has been introduced in OSP10 and OSP11 as a prerequisite for the fixes related to BZ 1454344 and BZ 1445436.

In OSP12 with the migration to ceph-ansible use of device aliases is also supported but the parameter to use is different.

My idea was to add a small note in the deployment examples saying it is possible to use device aliases.

Comment 13 Lucy Bopf 2018-02-21 04:33:37 UTC
Change has been published.

Closing


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