On 20/03/2015 05:39, kefu chai wrote:
to pave the road to http://tracker.ceph.com/issues/10904, where we
need to add a command to list the hostname of nodes in a ceph cluster,
i would like to add the "{mds,mon} metadata" commands to print the
system information including, but not limited to hostname,
mem_{total,swap}_kb, and distro info, of specified mds and mon.
the implementation follow the mechanism of "osd metadata":
on the mds side i would like to reuse the MDSMonitor service:
1. piggy back a map for the metadata in MMDSBeacon message,
2. put the metadata into the same DBStore transaction but with another
prefix when storing the pending inc into local storage.
3. and expose it using the "mds metadata" and later on the "service
ls" (not sure about the name ...)
@greg and @zyan, are you good with this? not sure this will overburden
the mds or not. i will use uname(2) and grep /proc/meminfo to get the
metadata in the same way of OSD.
It should be straightforward to include the metadata in MMDSBeacon only
once per daemon lifetime, by checking if state is CEPH_MDS_STATE_BOOT --
that way we don't have to worry about any ongoing costs. I expect that
change can live entirely in Beacon.cc without touching any other MDS code.
As for the means of getting the information, I expect the generic
kernel/mem/cpu/distro stuff from OSD::_collect_metadata can be moved up
into common/ somewhere and reused as-is from mon+mds.
John
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