Monday, June 16, 2014

Getting ceph and rados running

I finally managed to get a rados gw going (it's a service exposing an S3 like API), so that you can access files on the huge cluster through a webserver. There were some issues where radosgw couldn't connect to ceph, but that was eventually resolved.

radosgw essentially creates new pools in ceph and at startup it does this incrementally. If this pool isn't healthy, apparently updates to it are stalled and processes that use it seem to halt. What I did to remedy it was to set the replication level to 1 for all pools. Here's my output:

# ceph osd lspools
0 data,1 metadata,2 rbd,3 .rgw.root,4 .rgw.control,5 .rgw,6 .rgw.gc,7 .users.uid,8 .users,
When you use this command:

# radosgw-admin user create --uid=johndoe --display-name="John Doe"

It stalls when .users is not set yet and this is created after you rerun.

So a remedy here is to start ceph and rados, keep looking for new pools when you continue on the tutorial and set the replication level to 1. There should be another way to create new pools with the level set correctly from the start.

# ceph osd pool set size 1

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