> Thank you for the prompt response. > > > Such a heterogenous setup is only possible with a large number of OSDs > > A heterogeneous setup is exactly what I am testing for. I wonder if the balancer will actually consider the WEIGHT when allocating the data to OSD. It does, but only when the highest ranking "problem" is solved, which is "place one copy on each host" and you have 3 copies and 3 hosts. > Let's say I have 3 hosts, with 10 OSDs in each host. 1st and 2nd host has an equivalent size, 10 TB each host, while 3rd host has 20TB. > In this scenario what will happen? Is it still the same where the 1st and 2nd host will hit storage full while leaving 10TB in the 3rd host? > > If so, we should always try our best to balance the hosts to have similar storage space? If 3 hosts is the absolute maximum, then yes, they should be equally large, otherwise the smallest OSD host will be limiting your total size. Now, if you have 4 hosts (a good idea for production clusters with repl=3) and you have two with 10TB and two with 5TB each, it would be possible for ceph to put more on the two larger hosts and less on the two smaller ones. There are sometimes other factors that could make such a cluster choose poorly, but overall it would work. The more OSD hosts you get, the better the data can spread out over all of them, while still respecting the hard limit of "3 copies, never two copies on the same host". -- May the most significant bit of your life be positive. _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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