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Dell HPC Lustre Storage solution with Mellanox Infiniband EDR
Figure 11: N-to-N Random reads and writes
4.3 Metadata Testing
Metadata testing measures the time to complete certain file or directory operations that return
attributes. MDtest is an MPI-coordinated benchmark that performs Create, Stat, and Remove
operations on files or directories. This study used MDtest version 1.9.3. The MPI stack used for this
study was the Intel MPI distribution. The metric reported by MDtest is the rate of completion in terms
of operations per second (OP/sec). MDtest can be configured to compare metadata performance for
directories and files. However, due to time constraints in testing, we only performed passes of files
operations.
On a Lustre file system, OSTs are queried for object identifiers in order to allocate or locate extents
associated with the metadata operations. This interaction requires the indirect involvement of OSTs in
most metadata operations. In lab experiments with the test bed, it was found that using OST count of 1
was more efficient for most metadata operations, especially for higher thread counts. The experiments
consisted of conducting tests, with up to 32 clients for the following Lustre topologies (results not
presented here), to select the most efficient configuration for the metadata performance tests for this
version of the solution:
1 OST, 1MB Stripes
1 OST, 4MB Stripes
24 OSTs, 1MB Stripes
24 OSTs, 4MB Stripes
The most efficient configuration was found to be with 1 OST with 1MB stripes, therefore the results
presented in this section were obtained with this Lustre topology.
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Iozone Random - Dell HPC Lustre Storage with Infiniband EDR
Read Write