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School of Computer Science & Engineering
University of New South Wales
 Advanced Operating Systems 
 COMP9242 2002/S2 

Limitations of Traditional File Systems

Observations:

• Many write operations required for some function (file creation):
  • 5 writes, 2 synchronous (inode (2), dir, dir's inode, data).

• Seeks are expensive:
  • Average seek costs as much as 100's of kB of data transfer.

• Big caches eliminate most reads:
  • Write costs become critical.

How can we eliminate

• synchronous writes, and
• seeks on writes?
  

Normal logging helps only partially.