Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

Virtual Log Based File Systems for a Programmable Disk

Randolph Y. Wang, Thomas E. Anderson and David A. Patterson

EECS Department
University of California, Berkeley
Technical Report No. UCB/CSD-98-1031
1998

http://www.eecs.berkeley.edu/Pubs/TechRpts/1998/CSD-98-1031.pdf

In this paper, we study how to minimize the latency of small transactional writes to disk. The basic approach is to write to free sectors that are near the current disk head location by leveraging the embedded processor core inside the disk. We develop a number of analytical models to demonstrate the performance potential of this approach. We then present the design of a variation of a log-structured file system based on the concept of a virtual log, which supports fast small transactional writes without extra hardware support. We compare our approach against traditional update-in-place and logging systems by modifying the Solaris kernel to serve as a simulation engine. Our evaluations show that random updates on an unmodified UFS execute up to an order of magnitude faster on a virtual log than on a conventional disk. The virtual log can also significantly improve LFS in cases where delaying small writes is not an option or on-line cleaning would degrade performance. If the current trends of disk technology continue, we expect the performance advantage of this approach to become even more pronounced in the future.


BibTeX citation:

@techreport{Wang:CSD-98-1031,
    Author = {Wang, Randolph Y. and Anderson, Thomas E. and Patterson, David A.},
    Title = {Virtual Log Based File Systems for a Programmable Disk},
    Institution = {EECS Department, University of California, Berkeley},
    Year = {1998},
    URL = {http://www.eecs.berkeley.edu/Pubs/TechRpts/1998/6417.html},
    Number = {UCB/CSD-98-1031},
    Abstract = {In this paper, we study how to minimize the latency of small transactional writes to disk. The basic approach is to write to free sectors that are near the current disk head location by leveraging the embedded processor core inside the disk. We develop a number of analytical models to demonstrate the performance potential of this approach. We then present the design of a variation of a log-structured file system based on the concept of a virtual log, which supports fast small transactional writes without extra hardware support. We compare our approach against traditional update-in-place and logging systems by modifying the Solaris kernel to serve as a simulation engine. Our evaluations show that random updates on an unmodified UFS execute up to an order of magnitude faster on a virtual log than on a conventional disk. The virtual log can also significantly improve LFS in cases where delaying small writes is not an option or on-line cleaning would degrade performance. If the current trends of disk technology continue, we expect the performance advantage of this approach to become even more pronounced in the future.}
}

EndNote citation:

%0 Report
%A Wang, Randolph Y.
%A Anderson, Thomas E.
%A Patterson, David A.
%T Virtual Log Based File Systems for a Programmable Disk
%I EECS Department, University of California, Berkeley
%D 1998
%@ UCB/CSD-98-1031
%U http://www.eecs.berkeley.edu/Pubs/TechRpts/1998/6417.html
%F Wang:CSD-98-1031