On Wed, 11 Sep 2019 at 23:31, Sage Weil <sage@newdream.net> wrote:
On Wed, 11 Sep 2019, Rishabh Dave wrote:
Hello,
While working on CephFS Quick Start guide[1], the major issue that I came across was choosing the value for pg_num for the pools that will serve CephFS. I've tried the values from 4 to 128 for both data and metadata pools and have always got "undersized+peered" instead of "active+clean". Copying pg_num values from the cluster setup by vstart.sh (8 for data and 16 for metadata pools) gave me the same result.
About the cluster: I had a single node running Fedora 29 with 1 MON, 1 MGR, 1 MDS and 3 OSDs each with a disk size of 10 GB. Thinking that
This is unrelated to the PGs or the capacity--the problem is that you have a single node, and the default CRUSH rule replicates across hosts. That's why your pools are unhealthy.
You can fix this by creating a new crush rule with 'osd' instead of 'host' as the failure domain, and then setting your pool(s) to use that rule.
osd crush rule create-replicated <name> <root> create crush rule <name> for replicated pool to <type> {<class>} start from <root>, replicate across buckets of type <type>, use devices of type <class> (ssd or hdd)
osd pool set <poolname> crush_rule <rule-name>
sage
Both, setting the new crush rule to pools and creating OSDs on separate nodes worked. Thanks! However, in both cases the PG status wasn't "active+clean". It was "54 active+undersized" and "10 active+undersized+degraded". IMO, it would ideal for CephFS Quick Start guide to lead to "active+clean". Is there anything more that can be done and would be suitable for the guide?