Il giorno gio 10 mag 2018 alle ore 09:48 Christian Balzer <chibi@xxxxxxx> ha scritto: > Without knowing what your use case is (lots of large reads or writes, or > the more typical smallish I/Os) it's hard to give specific advice. 99% VM hosting. Everything else would be negligible and I don't care if not optimized. > Which would give you 24 servers with up to 20Gb/s per server when both > switches are working, something that's likely to be very close to 100% > of the time. 24 servers between hypervisors and storages, right ? Thus, are you saying to split in this way: switch0.port0 to port 12 as hypervisor, network1 switch0.port13 to 24 as storage, network1 switch0.port0 to port 12 as hypervisor, network2 switch0.port13 to 24 as storage, network2 In this case, with 2 switches I can have a fully redundant network, but I also need a ISL to aggregate bandwidth. > That's a very optimistic number, assuming journal/WAL/DB on SSDs _and_ no > concurrent write activity. > Since you said hypervisors up there one assumes VMs on RBDs and a mixed > I/O pattern, saturating your disks with IOPS long before bandwidth becomes > an issue. Based on a real use-case, how much bandwidth should I expect with 12 SATA spinning disks (7200rpm) in mixed workload ? Obviously, a sequential read would need about 12*100MB/s*8 mbit/s > The biggest argument against the 1GB/s links is the latency as mentioned. 10GBe should have 1/10 latency, right ? Now, as I'm evaluating many SDS and Ceph, on the paper, is the most expensive in terms of needed hardware, what do you suggest for a small (scalable) storage, starting with just 3 storage servers (12 disks each but not fully populated), 1x 16ports 10GBaseT switch, (many) 24ports Gigabit switch and about 5 hypervisors servers ? _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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