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Results of File System Workloads
Figure 14:
Comparison of the performance of different
array alternatives under two file system workloads: (a) Cello disk
2, housing ``/users'', and (b) Cello disk 6, housing
``/var/spool/news''. Each data point represents the performance of
the best configuration based on a given array alternative.
The rectangular labels show the degree of mirroring (or replication)
used in the configurations. The unlabeled configurations in the second
figure have identical degrees of mirroring (or replication) as their
counterparts in the first figure.
![\begin{figure}
\centerline {\psfig{figure=figs/cello.eps,width=3.1in,clip=}}
\hspace{0.8in}(a)\hspace{1.4in}(b)
\end{figure}](img55.png) |
Although the target workload of an EW-Array is TPCC-like transaction
processing applications, it is natural to ask whether it works for
other workloads. Figure 14 shows the performance results
of two file system workloads that are selected from the HP ``Cello''
trace. Cello is a two month trace of a file server supporting
simulations, compilations, editing, and reading mail and news. We use
the traces of two disks during the week from 5/30/92 to 6/6/92. Disk
2 houses user home directories and disk 6 houses a news archive. To
compensate for the relatively lower I/O rates of the trace, we speed
up the trace playing rate by a factor of four.
The difference between Figure 14(a) and (b) is
due to the different locality
and the different read/write ratio of the two workloads.
Cello disk
2 exhibits a higher degree of locality: the average seek distance on this
disk is about half of that of disk 6. Cello disk 6, on the other
hand, experiences a higher write ratio: 63.2% on disk 6 versus
45.2% on disk 2.
Therefore, an SR-Array performs best for disk 2 by preserving locality
and balancing the reduction of seek and rotational delays; while an
EW-Array excels for disk 6 by aggressively optimizing write latency.
Next: Related Work
Up: Experimental Results
Previous: Effect of the Delayed
Chi Zhang
2001-11-16