Improving NFS Performance on HPC Clusters with Dell Fluid Cache for DAS
2.5.3. Dell Fluid Cache for DAS health and monitoring
DFC provides a very simple command-line utility /opt/dell/fluidcache/bin/fldc that can be
used for configuration and management. Alternately, the DFC configuration can be accomplished using
the OMSA GUI. DFC is a component under the storage sub-section of the OMSA GUI.
/opt/dell/fluidcache/bin/fldcstat is a command-line utility that provides extensive statistics
of the cache hits on the system, disk IO, etc.
Additional details are available in the DFC User's Guide in [3].
3. Performance
This section presents the results of performance tests conducted on the storage solution described in
Section 2. Performance tests were run to evaluate the following common I/O patterns.
•
Large sequential reads and writes
•
Small random reads and writes
•
Metadata operations
These tests were performed over the IP-over-InfiniBand (IPoIB) network as described in Section 2.3.
The iozone and mdtest benchmarks were used for this study. Details of the benchmarks and test
process are provided in Appendix B: Benchmarks and tests.
Iozone was used for the sequential tests as well as the random tests. The I/O access patterns are N-to-
N, i.e., each thread reads and writes to its own file. Iozone was executed in clustered mode and one
thread was launched on each compute node. For the sequential tests, the performance metric used
was throughput in terms of MiB/s. For random tests, I/O operations per second (IOPS) was the metric.
The large sequential read and large sequential write tests were conducted using a request size of 1024
KB. The total amount of data written was 256 GB. (Recall from Table 1 that the NFS server RAM is 128
GB.) This is to ensure that the total I/O exceeds the NFS server memory since the goal is to test the
disk and storage solution performance.
The small random tests were performed with 4 KB record sizes since the size corresponds to typical
random I/O workloads. Each client reads and writes a smaller 4 GB file for these tests.
The metadata tests were performed with the mdtest utility and include file creates, stats, and
removals.
While these benchmarks do not cover every I/O pattern, they help characterize the I/O performance of
this storage solution.
Each set of tests was run on a range of clients to test the scalability of the solution. The number of
simultaneous clients involved in each test was varied from one to 64 clients. The client test bed is
described in Section 2.3.
Tests were performed on three configurations:
•
Baseline - This is the pure NFS storage solution as described in Section 2.1.
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