VMware, Inc.
Using segment pre-allocation to support large segments

Abstract:

Techniques for supporting large segments when issuing writes to an erasure coded storage object in a distributed storage system are provided. In one set of embodiments, a node of the system can pre-allocate a segment of space in a capacity object of the storage object, receive a write request for updating a logical data block of the storage object, write data/metadata for the block to a record in a data log of a metadata object of the storage object, place the block in an in-memory bank, and determine whether the in-memory bank has become full. If so, the node can compute/fill-in one or more parity blocks for each stripe of the storage object in the in-memory bank and write, based on a next sub-segment pointer pointing to a free sub-segment of the pre-allocated segment, the contents of the in-memory bank via a full stripe write to the free sub-segment.