Hi ceph users: I want to create a customized crush rule for my EC pool (with replica_size = 11) to distribute replicas into 6 different Racks. I use the following rule at first: Step take default // root Step choose firstn 6 type rack // 6 racks, I have and only have 6 racks Step chooseleaf indep 2 type osd // 2 osds per rack Step emit I looks fine and works fine when PG num is small. But when pg num increase, there are always some PGs which can not take all the 6 racks. It looks like ?Step choose firstn 6 type rack? sometimes returns only 5 racks. After some investigation, I think it may caused by collision of choices. Then I come up with another solution to solve collision like this: Step take rack0 Step chooseleaf indep 2 type osd Step emit Step take rack1 ?. (manually take every rack) This won?t cause rack collision, because I specify rack by name at first. But the problem is that osd in rack0 will always be primary osd because I choose from rack0 first. So the question is what is the recommended way to meet such a need (distribute 11 replicas into 6 racks evenly in case of rack failure)? Thanks! LeiDong -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140909/ecb11638/attachment.htm>
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