Hp StorageWorks Scalable File Share User Manual download pdf (Page 74)

For workloads that require a lot of disk head movement relative to the amount of data moved,

SAS disk drives provide a significant performance benefit.

Random writes present additional complications beyond those involved in random reads. These

additional complications are related to Lustre locking, and the type of RAID used. Small random

writes to a RAID6 volume requires a read-modify-write sequence to update a portion of a RAID

stripe and compute a new parity block. RAID1, which does not require a read-modify-write

sequence, even for small writes, can improve performance. This is why RAID1 is recommended

for the MDS.

A.7 DDR InfiniBand Performance Using MSA2312 with Three Attached

JBODs

This section provides results of tests performed with two MSA2312 controllers, each with three

attached expansion shelf JBODs, also known as deep shelf configuration. Tests were run with

HP SFS G3.1-0 and MVAPICH2. The OSTs were populated with 450 GB SATA drives. Stripe

placement was controlled by default operation of the HP SFS file system software. Specific control

of striping can affect performance. Due to variability in configuration, hardware, and software

versions, it is not valid to directly compare the results indicated in this section with those indicated

in other sections.

A.7.1 Benchmark Platform

The client configuration for deep shelf testing is shown in Figure A-10. Solid grey lines indicate

DDR IB connections. The head node launched the tests but did not access the HP SFS file system

while tests were in progress.

Figure A-10 Deep Shelf DDR IB Test Configuration

74 HP SFS G3 Performance

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Hp StorageWorks Scalable File Share User Manual Page 74