File System Performance Enhancements

The HFS file system uses block based allocation schemes which provide adequate random access and latency for small files but limit throughput for larger files. As a result, the HFS file system is less than optimal for commercial environments.

VxFS addresses this file system performance issue through an alternative allocation scheme and increased user control over allocation, I/O, and caching policies. An overview of the VxFS allocation scheme is covered in the section “Extent-Based Allocation” on page 5.

VxFs provides the following performance enhancements:

extent based allocation
enhanced mount options
data synchronous I/O
direct I/O and discovered direct I/O
caching advisories
enhanced directory features
explicit file alignment, extent size, and preallocation controls
tuneable I/O parameters
tuneable indirect data extent size
The rest of this chapter along with Chapter 5 “Performance and Tuning ” and Chapter 6 “Application Interface” provide more details on some of these features.

File System Performance Enhancements

Technical documentation

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