1. An apparatus comprising: a compute node of a parallel file system; the compute node being configured to communicate with a plurality of object storage servers and with a plurality of other compute nodes over a network, wherein a plurality of applications executing on said plurality of compute nodes generate a shared file; the compute node further configured to implement a Parallel Log Structured File System (PLFS) library to store at least one portion of said shared file generated by an application executing on said compute node and PLFS metadata for said at least one portion of said shared file on one or more of said plurality of object storage servers, wherein said PLFS metadata for said at least one portion of said shared file comprises a key-value pair having a key based on a logical offset of said at least one portion of said shared file; the compute node further configured to implement a partitioned key-value data store for storing a partition of said PLFS metadata for said shared file, wherein said partitioned key-value data store communicates with partitioned key-value data stores on said other compute nodes using a message passing interface to cooperatively store the PLFS metadata, wherein said partition comprises a given sub-range of a key space for said PLFS metadata, wherein said key-value pair for said PLFS metadata for said at least one portion of said shared file is inserted into a corresponding one of said partitions stored by a respective partitioned key-value data store as a new key-value record based on said key when said at least one portion is written to said shared file; and the compute node being implemented utilizing at least one processing device coupled to a memory.