Hi + question

Hi + question

[Roald van Loon]

Hi list,

I'm looking into ceph, and I must say I'm really delightful to see a
decent integrated object/file storage system being developed as an
open source project.

I'm a C (+ sometimes python developer) and currently looking for a
nice project to maybe invest some of my evening hours in. Did some
kernel hacking in the past (nothing upstream though, was mostly
specific for the employer's environment), worked at a 3000+ nodes
website company (most of them being photo/video storage nodes and most
others being db nodes), and I remember looking at your project some
years back. Happy to see it actually evolved quite nicely. My
compliments to the devs!

Like I said I'm toying away with ceph since an hour or two, and one of
the things I noticed was that setting up my test env and getting to
know ceph wasn't all that easy to do (gentoo btw). Things like ceph -h
not showing the setcrushmap option, the 'ceph osd crush set' only
returning '(22) Invalid argument' etc etc... So, I decided to take a
real good look at the sources - any dev's number one source for
documentation :-) There I... well.. kind of got lost. Cpp files,
devops tools (python tools, shell scripts, perl scripts), fooclass,
barclass ofcourse, valgrind supps, ... all in ~/src :-)

So I was curious if I was the only one finding this a bit confusing.
If not, I was wondering if you have some clean-up subproject running
somewhere. Might be a nice way for me to really familiarize myself
with the code base.

Let me know,

Roald

Re: Hi + question

[Joao Eduardo Luis]

On 11/25/2012 07:02 PM, Roald van Loon wrote:
> Like I said I'm toying away with ceph since an hour or two, and one of
> the things I noticed was that setting up my test env and getting to
> know ceph wasn't all that easy to do (gentoo btw). Things like ceph -h
> not showing the setcrushmap option, the 'ceph osd crush set' only
> returning '(22) Invalid argument' etc etc... So, I decided to take a
> real good look at the sources - any dev's number one source for
> documentation :-) There I... well.. kind of got lost. Cpp files,
> devops tools (python tools, shell scripts, perl scripts), fooclass,
> barclass ofcourse, valgrind supps, ... all in ~/src :-)
> 
> So I was curious if I was the only one finding this a bit confusing.
> If not, I was wondering if you have some clean-up subproject running
> somewhere. Might be a nice way for me to really familiarize myself
> with the code base.
> 
> Let me know,
> 
> Roald

Welcome Roald!

I must say I can relate to that feeling, from back when I started
working with ceph. But I guess that most of my early confusion was
basically due to not being aware where the stuff I wanted was located.

Nowadays I find the sources division fairly consistent with their
purpose. See, in src/ you will mostly find the daemons and the tools; on
mon/ you will find the files that are mostly mon-related, and same goes
for most of the other subdirectories (osd/, mds/, crush/,...). There are
a couple of exceptions, such as global/ or common/, but those by
themselves are pretty self-explanatory ;-)

To be honest, the only thing that keeps annoying me is that the build
process will end up leaving all the objects, libraries and binaries in
src/ after the build, but that's one of the things I've learned to live
with without trying to find an alternative (shame!).

If you need pointers on how to get familiarized with the code base, or
any doubts arise, just let us know and we'd be pleased to point you in
the right direction. You might also find it useful to join us on #ceph
at OFTC.

And, fwiw, the 'ceph' tool itself (which is on tools/, btw), won't
provide you the insight you're looking for. It mostly sends commands
directly to the monitor, and the monitor will send replies the tool will
output. What you are looking for, in this case, can be found on
mon/OSDMonitor.cc


Cheers,
  -Joao