The chart to the left was sent out in last months SCI newsletter and shows the throughput attained by various storage systems when running the SPECsfs(R) 2008 CIFS and NFS benchmarks. The scatter-plot shows data for NAS systems that have published both NFS and CIFS SPECsfs benchmark results for the same storage system. To date (June 2009), only 5 systems have published results for both benchmarks.
The scatter plot clearly shows with a high regression coefficient (.97) that the same system can typically provide over 2.4X the throughput using CIFS as it can using NFS. My friends at SPECsfs would want me to point out that these two benchmarks are not intended to be comparable and I present this with a few caveats in the newsletter:
- NFS operations are stateless and CIFS are stateful, the distribution of file sizes are different for the two benchmarks, the relative proportions of the respective IO workloads don’t match up exactly (CIFS has more reads and less writes than NFS), and all remaining (non-read/write) operations are completely different for each workload.
- Most of these results come from the same vendor (Apple) and it’s implementation of NFS or CIFS target support may skew results
- Only 5 storage systems have published results for these two benchmarks and probably in all honesty do not represent a statistically valid comparison
- Usually host implementations of CIFS or NFS impact results such as these but for SPECsfs, the benchmark implements each protocol stack. As such, SPECsfs benchmark’s implementation of CIFS or NFS protocols may also skew results
All that being said, I believe it’s an interesting and current fact that for SPECsfs 2008 benchmarks CIFS has 2.4X the throughput of NFS.
In talking with real world customers and vendors on which is better the story seems much more mixed. I heard where one O/S had a much better implementation of the CIFS protocol and as such, customers moved to use CIFS for those systems. I haven’t seen much discussion about storage systems being better or worse on one protocol over the other but it’s certainly probable.
From my perspective any storage admin looking to configure new NAS storage should try out CIFS first to see if it performs well before trying NFS. Given my inclinations, I would probably try out both, but that’s just me.
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Otherwise the full report will be on my website sometime next week.