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Dell HPC NFS Storage Solution High Availability Configurations with Large Capacities

6.5. NFSv3 compared to NFSv4

During the design and analysis of the NSS-HA solution it was found that NFSv3 provides better

performance than NFSv4 for certain scenarios. This section describes the deltas in performance

between NFSv3 and NFSv4. In certain situations the security enhancements of NFSv4 might be more

important than any loss in performance. The results presented in this section help quantify the

performance loss and pinpoint the scenarios where a difference in performance can be expected.

For the three types of IO workloads tested in this study, it was found that the most dramatic difference

between NFSv3 and NFSv4 performance was in the metadata file create tests. These results are

presented later in this section in Figure 18. Metadata file stat were measured to be within 15% of each

other for NFSv3 and NFSv4; NFSv3 performed better for low client counts and NFSv4 performed better

for the higher client counts. Metadata remove operations were 10 – 28% faster with NFSv3.

Figure 18 compares NFSv3 and NFSv4 performance on the metadata file create tests. As seen from the

graph, the 144TB and 288TB configurations perform the same with either protocol version, i.e., the

capacity of the configuration does not matter, the NFS protocol version is the main differentiator.

NFSv3 performance is an order of magnitude better than NFSv4. NFSv4 file creates saturate at about

1550 create operations per second. With NFSv3, the peak performance is close to 34000 create

operations per second. With the current version of NFSv4 the state locking implementation causes the

file create operations to be serialized, hindering performance

(5)

. This issue is expected to be alleviated

in future versions.

InfiniBand NFSv3 and NFSv4 file create performance Figure 18.

5000

10000

15000

20000

25000

30000

35000

40000

45000

1 2 4 8 16 32 48 64 128 256 512

Number of create() per sec

Number of concurrent clients

IB File Create Performance

144TB -- NFSv3 288 TB -- NFSv3

144 TB -- NFSv4 288 TB -- NFS v4