Metadata management in large distributed systems is a
critical aspect of overall system performance. Directory
subtree partitioning and pure hashing are two common
techniques used for metadata management. Neither of
these techniques can support large systems with high concurrent
accesses due to the conflicting need for both load
balancing and directory update efficiency. We present
a flexible approach that addresses the problems of the
existing techniques. The approach, called Lazy Hybrid
Hashed Hierarchical directory management, takes advantage
of the load balancing and other performance benefits
of hashing, while maintaining a hierarchical directory
structure and metadata logging to support lazy metadata
relocation and updates. A dual-entry Access Control List
provides direct permission calculation to the target file,
avoiding the overhead of traversing the pathname for permission
check.
