Test Results

Table 2 lists the IOzone results for NFS and SSHFS from the previous article with the results for the five SSHFSM test sets:

• Baseline: Use all system and SSHFS-MUX defaults
• OPT1: SSHFS-MUX mount option tuning
• OPT2: OPT1 with TCP tuning
• OPT3: OPT2 with stronger encryption (aes-128)
• OPT4: OPT3 with compression turned on

To help visualize the data, the six bar charts in Figures 6-8 plot the results for all five test sets, one for each test.

Figure 6: Plot of Baseline, OPT1, OPT2, OPT3, and OPT4 IOzone results for NFS, SSHFS, and SSHFSM for the Sequential Write (top left), Sequential Re-write (top right), Sequential Read (bottom left), and Sequential Re-read (bottom right) tests.

Figure 7: Random Write IOPS test: plot of Baseline, OPT1, OPT2, OPT3, and OPT4 IOzone results for NFS, SSHFS, and SSHFSM.

Figure 8: Random Read IOPS test: plot of Baseline, OPT1, OPT2, OPT3, and OPT4 IOzone results for NFS, SSHFS, and SSHFSM.

Comparing the performance of SSHFS and SSHFSM is rather interesting. In general, the performance is quite close except in a couple of instances. For example, in the sequential write tests, SSHFSM is sometimes up to 5 percent faster than SSHFS. SSHFSM in the OPT4 results for the sequential re-write test is almost 9 percent faster than SSHFS. For the sequential read, re-read, and random read IOPS, SSHFS is sometimes slightly faster than SSHFSM. However, this comparison might not be that useful because the "spread" of the performance results is unknown, and one can't conclusively say one is faster than the others.

Comparing SSHFS and SSHFSM performance to NFS is perhaps more useful from a qualitative standpoint. When all the SSHFMS and TCP optimizations are used, SSHFS and SSHFSM has better write performance (sequential write and re-write, and random write IOPS). Even if a stronger encryption is used, which requires more computational capability, SSHFS and SSHFSM can be just as good or better than NFS for write tests. However, read performance for SSHFS and SSHFSM is worse or only close to NFS performance until compression is turned on (compression turned on results are OPT4). A remarkable result is that SSHFS and SSHFSM performance for the random read IOPS test is never better than about 60 percent that of NFS.

Summary

SSHFS has great potential as a shared filesystem. It encrypts data in flight, it allows users to control what filesystems they mount, and it only requires an open SSH port (port 22). With some tuning, you can get SSHFS performance on the same level as NFS, except for the random read IOPS performance. However, the price you pay is data encryption or decryption on both the client and server.

In the pursuit of even more performance, I tried SSHFS-MUX. SSHFSM is derived from SSHFS and has been extended to allow several directories to be mounted in a single mountpoint. I didn't test this feature, but I did test the performance of SSHFS-MUX relative to SSHFS. Although the tests I ran here are not as extensive as those I would perform for benchmarking, casual testing allowed me to gauge general performance differences. In some cases, SSHFS-MUX was a little faster than SSHFS, but it was fairly small, only about 5 percent for some cases.

For anyone considering using SSHFS, SSHFS-MUX, with its ability to combine directories from different servers into a single mountpoint, is a definite option.