Hello, I know somebody will ask me to open a tracker issue, etc, but I feel sufficiently frustrated to rant a bit here. Case in point: http://docs.ceph.com/docs/master/rados/operations/cache-tiering/ Let me start on a positive note, though. Somebody pretty recently added the much needed detail that you NEED to set the absolute size and that the relative options do depend on it. That will help a lot of people doing this for the first time. The whole thing is a bit sparse, the hit type has only one option, so why not default to it instead of having to set it manually? In the hit set section we get a example of: --- ceph osd pool set {cachepool} hit_set_count 1 ceph osd pool set {cachepool} hit_set_period 3600 ceph osd pool set {cachepool} target_max_bytes 1000000000000 --- The last one being out of place here, that bit is explained later and if people do cut/paste (cargo-culting) a likely mistake. Then we come to a typical problem for fast evolving SW like Ceph, things that are not present in older versions. If a new option/parameter is added, state clearly from which version this has been introduced. Neither "cache_target_dirty_high_ratio" nor "min_write_recency_for_promote" are present in the latest Hammer. The first one fills me with dread when thinking about the potential I/O storms when the cache gets full, the later removes some of the reasons why I would want to go to 0.94.6 for the recency fix. Regards, Christian -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Global OnLine Japan/Rakuten Communications http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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