Hi all, I have some questions about the Ceph multi-site implementation. I am thinking to have Ceph as the storage solution for across three internal site. I think, with a good internet connection, using the Multi-site object storage with RADOS (or RGW) might be a good use here. Thus, each site will have a MON node and many OSDs and replicate data between each other. With this implementation, I hope it will allow user to READ/WRITE from/to the local office and Ceph will take care the replication. So my question is: 1. How does Ceph know how to retrieve data from the nearest location? (As Ceph usually calculate where the data is through CRUSH rather than the nearest location for the user.) Will the data be distributed evenly throughout the three sites? If not, how can we let user to access the _local copy_ ? 2. Is " Multi-site object storage with RADOS" a good fit for their implementation? i.e. to READ/Write data To/From their local site? If not, what is the best way to approach this? 3. Does Ceph use the same ID (object name?) for all its replica? Can we access(read/write) these replica directly? 4. From this multi-site scenario, when a user write data to Ceph, will it find the nearest OSD to put the data? When a user read data, does it always respond from the primary data set (doesn't matter the location) or respond from the nearest replica copy? Thanks, Shang Wu
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