Hi, The config values bluestore_cache_size_ssd and bluestore_cache_size_hdd determine how much memory a OSD running with Bluestore will use for caching. By default the values are: bluestore_cache_size_ssd = 3GB bluestore_cache_size_hdd = 1GB I've seen some cases recently where users migrated from FileStore to BlueStore and had the OOM-killer come along during backfill/recovery siautions. These are the situations where OSDs require more memory. It's not uncommon to find servers with: - 8 SSDs and 32GB RAM - 16 SSDs and 64GB RAM With FileStore it was sufficient since the page cache did all the work, but with BlueStore each OSD has it's own cache which isn't shared. In addition there is the regular memory consumption and the overhead of the cache. I also don't understand the ideas behind the values. As HDDs are slower the usually require more cache then SSDs, so I'd expect the values to be flipped. My recommendation would be to lower the value to 1GB to prevent users from having a bad experience when going from FileStore to BlueStore. I have created a pull request for this: https://github.com/ceph/ceph/pull/20940 Opinions, experiences, feedback? Wido -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
