Thanks Craig,

I learned a bit more in the meantime.

On Tue, Jun 17, 2014 at 3:30 PM, Craig Lewis <[email protected]>
wrote:

> > 3. You must use MDS from the start, because it's a metadata
> > structure/directory that only gets populated when writing files through
> > cephfs / FUSE. Otherwise, it doesn't even know about other objects and
> > therefore isn't visible on cephfs.
> > 4. MDS does not get updated when radosgw / S3 is used.
>
> You can use MDS whenever you want to start using CephFS.  CephFS and
> RadosGW are indepenent, they use different pools.  Data added to
> RadosGW is not visible to CephFS, and data added to CephFS is not
> visible to RadosGW.
>
> It's all visible to RADOS, because both are implemented on top of
> RADOS.  More on that later.


Just to clarify. Suppose you insert an object into rados directly, you
won't be able to see that file
in cephfs anywhere, since it won't be listed in MDS. Correct?

Meaning, you can start using CephFS+MDS at any point in time, but it will
only ever list objects/files
that were inserted through cephfs/FUSE, nothing else.?

If that's not the case, how do those objects appear in cephfs?



>
> > So my questions are:
> > * radosgw uses the ".bucket" pool for managing and controlling which
> buckets
> > there are?
>
> By default, RadosGW uses .rgw, .rgw.buckets.index, and .rgw.buckets.
> Once you start creating RadosGW users, it will create some more pools,
> depending on which of the features you're using.
>
> You can create different pools (using placement targets), and assign
> users and buckets to them.  The common example is one user's data
> should be on SSDs, and another user should be on HDDs.
>
>
I've seen these pools being created now and managed to successfully upload
files and query them
through S3. I even set quotas on users and buckets, which is a great
feature.


>
> RadosGW breaks every file up into a 4M chunk.  With enough effort, you
> could reconstruct the bucket and object manually.  I've done it once
> (to prove I could), but I don't plan to do it again.
>


Yes... in other words.. practically files inserted through S3 are only
usable by radosgw from there on.
As S3 and Swift are just interfaces to tlak to radosgw, I believe objects
added through S3 are also visible
on Swift?

> * Are there alternatives for accessing the radosgw information besides
> going
> > through the S3 interface (command line)?
>
> I've been using s3cmd for command line access and general maintenance.
> It's a python script that talks to the S3 interface though, so you'll
> still need a website.
>

When adding the S3/Swift users, I noticed that radosgw-admin is capable of
a lot more. The use of how the commands
are tied together though isn't very intuitive and I had to rely on examples
to get things done.

I'm now figuring out how to use that so I can list the size of a single
bucket and user.

Rgds,

Gerard
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