test/librados/cmd.cc: tolerate thrashing on pg_command tests

We may get ENXIO (osd down) or ENOENT (pg dne (yet) on the target osd) if
there is thrashing going on.

Fixes: #6122
Signed-off-by: Sage Weil <sage@inktank.com>
doc: Excised content from "Getting Started" and created Intro to Ceph.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Added Intro to Ceph to Index.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated for 3-node deployment and multiple Linux distributions.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Removed introductory material. Renamed the page.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated for 3-node deployment. Leaner discussion. More use cases.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Made sysvinit and service sections parallel to upstart for clarity.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated link to Storage Cluster Quick Start.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated link to Storage Cluster Quick Start.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated link to Storage Cluster Quick Start.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Moved recommendations sections to Intro.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Changed title, and removed recommendations sections.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Removed Get Involved from Quick Start.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Added Recommendations and Get Involved to Intro.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated graphic to use same name as command line examples.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated graphic. Removed bullet points. Cleaned up RPM/YUM example.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Updated diagrams, refactored text.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Refactored diagram and text.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
rgw: quota utility class

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
rgw: more quota utility stuff

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>