[ceph-users] sub-read of librados

Hi! I am trying to read only part of an object by specifying the non-trivial offset and length of the read function: `librados::IoCtxImpl::read(const object_t& oid, bufferlist& bl, size_t len, uint64_t off)` from `IoCtxImpl.cc`. However, after connecting to an erasure code pool (e.g., 12+4), I try to read data from a randomly chosen OSD (that is, 1/12 of the object), but the results of command `vmstat -d` and `iostat` show that the entire object was read, since read operations appeared on all 12 OSDs. So, I wonder if librados doesn't support the real sub-read of an object, and what should I do if I want to implement this function. Thanks!