Sorry about the misused term 'OSS: object storage server' (a term often used in Lustre filesystem), what I meant is 4 hosts, each manages 12 OSDs. Thanks for anyone who may answer any of my questions.
Best, Jialin NERSC/LBNL On Sun, Jun 17, 2018 at 11:29 AM Jialin Liu <jaln...@lbl.gov> wrote: > Hello, > > I have a couple questions regarding the IO on OSD via librados. > > > 1. How to check which osd is receiving data? > > 2. Can the write operation return immediately to the application once the > write to the primary OSD is done? or does it return only when the data is > replicated twice? (size=3) > > 3. What is the I/O size in the lower level in librados, e.g., if I send a > 100MB request with 1 thread, does librados send the data by a fixed > transaction size? > > 4. I have 4 OSS, 48 OSDs, will the 4 OSS become the bottleneck? from the > ceph documentation, once the cluster map is received by the client, the > client can talk to OSD directly, so the assumption is the max parallelism > depends on the number of OSDs, is this correct? > > > Best, > > Jialin > >
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