On Fri, 5 Jun 2015, Handzik, Joe wrote:
> Adding in ceph-devel, this time without html formatting...
> 
> Rest-of-community,
> 
> After talking to Gregory, we can see any of the solutions in the original 
> email being acceptable, but it depends on what others are using and how 
> changes would affect them. 
> 
> 1. Is anyone actively using the 'osd metadata' monitor command?
> 2. Would anyone be upset if the data from 'osd metadata' came along for the 
> ride in 'osd dump'? (see: 
> https://github.com/ceph/ceph/blob/master/src/mon/OSDMonitor.cc#L3006 and 
> https://github.com/ceph/ceph/blob/master/src/mon/OSDMonitor.cc#L2910 )
> 3. Or, would a better solution be to push device, partition, and filesystem 
> information into the 'osd dump' dataset, and leave 'osd metadata' out of it? 
> (some of this stuff would move elsewhere: 
> https://github.com/ceph/ceph/blob/master/src/osd/OSD.cc#L4521 )
> a. Some of the data in the metadata bundle looked interesting, that's another 
> motivating factor behind carrying it with the device and partition data in my 
> current PR: https://github.com/ceph/ceph/pull/4699. Might be a better fit for 
> a different location though, seems overkill for every OSD to push this much 
> system data up.
> 4. Or, is everything so fragile that we should just add an 'osd metadata' 
> call into Calamari (alongside the 'osd dump' call: 
> https://github.com/ceph/calamari/blob/0964ec9b82c1182e97f00b13dc157f328f75e294/salt/srv/salt/_modules/ceph.py#L367
>  )

It is perhaps an implementation artifact, but: 'osd dump' is dumping 
(just) the contents of the OSDMap structure, and matches what you would 
get from

 ceph osd getmap -o foo
 osdmaptool --print foo  (or --print-json)

We definitely don't want the 'osd metadata' stuff to go in the OSDMap.

Exposing 'osd metadata' seems like the simplest thing?

sage

 
> Sorry for the link explosion, just trying to carry some context along. Any 
> (well, most) opinions would be appreciated!
> 
> Joe
> 
> From: Handzik, Joe 
> Sent: Friday, June 05, 2015 10:28 AM
> To: [email protected]
> Cc: Dan Mick ([email protected])
> Subject: Thoughts about metadata exposure in Calamari
> 
> Hey guys,
> 
> I finally feel like I have my head wrapped around how this works. I feel like 
> I have two general paths that I could go down now:
> 
> 1. In calamari, use the 'osd metadata' command to pull the metadata up. The 
> task here would be to figure out the right way to arrange that data (this 
> might actually kickoff the start of Gregory's hardware API concept). 
> a. My concern here is that metadata is a poorly-defined blob of string pairs. 
> It's not a well-defined structure like some of the other data that is exposed 
> today via other commands ('osd dump').
> 2. Speaking of 'osd dump', another option would be to make the metadata 
> bundle a first-class citizen of the dataset that is exposed via 'osd dump'. 
> This would obviously require changes in OSDMap and probably OSD itself, but 
> then the data would come along for free via the existing 'osd dump' command.
> 3. A hybrid of these two would be to define the metadata via a structure 
> instead of the set of string pairs that it is today, but still plan to add an 
> 'osd metadata' call into Calamari like in option #1.
> a. This might be the best option, but requires changes in both Ceph and 
> Calamari. I'd probably make the Ceph changes first, so I don't need to 
> implement option #1 first and then move something more like #3.
> 
> Lemme know if any of this seems off. No need to reply now, this is intended 
> as background information to clarify my thought process in the meeting today. 
> Still waiting on Sage to approve my existing pull request, but after a rocky 
> hour earlier in the week (hadn't tested -with-debug, apparently), I believe 
> I'm done.
> 
> Joe
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