On 03/07/18 13:08, John Spray wrote: > Right: as you've noticed, they're not spurious, they're where we keep > a "backtrace" xattr for a file. > > Backtraces are lazily updated paths, that enable CephFS to map an > inode number to a file's metadata, which is needed when resolving hard > links or NFS file handles. The trouble with the backtrace in the > individual data pools is that the MDS would have to scan through the > pools to find it, so instead all the files get a backtrace in the root > pool. Given this, the warning "1 pools have many more objects per pg than average" will happen ALWAYS. Is there any plan to do some kind of special case for this situation or a "mon_pg_warn_max_object_skew" override will be needed forever?. >> Should this data be stored in the metadata pool? > > Yes, probably. As you say, it's ugly how we end up with these extra [...] > One option would be to do both by default: write the backtrace to the > metadata pool for it's ordinary functional lookup purpose, but also > write it back to the data pool as an intentionally redundant > resilience measure. The extra write to the data pool could be > disabled by anyone who wants to save the IOPS at the cost of some > resilience. This would be nice. Another option would be simply use less objects, but I guess that could be a major change. Actually, my main issue here is the warning "1 pools have many more objects per pg than average". My cluster is permanently in WARNING state, with the known consequences, and my "mon_pg_warn_max_object_skew" override is not working, for some reason. I am using Ceph 12.2.5. Thanks for your time and expertise! -- Jesús Cea Avión _/_/ _/_/_/ _/_/_/ jcea@xxxxxxx - http://www.jcea.es/ _/_/ _/_/ _/_/ _/_/ _/_/ Twitter: @jcea _/_/ _/_/ _/_/_/_/_/ jabber / xmpp:jcea@xxxxxxxxxx _/_/ _/_/ _/_/ _/_/ _/_/ "Things are not so easy" _/_/ _/_/ _/_/ _/_/ _/_/ _/_/ "My name is Dump, Core Dump" _/_/_/ _/_/_/ _/_/ _/_/ "El amor es poner tu felicidad en la felicidad de otro" - Leibniz
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