We made a mistake in our last post discussing CIFS vs. NFS results using SPECsfs2008 benchmarks by including some storage systems that had SSDs in this analysis. All of our other per spindle/disk drive analyses exclude SSDs and NAND cache because they skew per drive results so much. We have corrected this in the above chart which includes all the SPECsfs2008 results, up to the end of last month.
However, even with the corrections the results stand pretty much the way they were. CIFS is doing more throughput per disk drive spindle than NFS for all benchmark results not using SSDs or Flash Cache.
Dropping SSD results changed the linear regression equation. Specificall, the R**2 for CIFS and NFS dropped from 0.99 to 0.98 and from 0.92 to 0.82 and the B coefficient dropped from 463 to 405 and from 296 to 258 respectively.
I would be remiss if I didn’t discuss a few caveats with this analysis.
- Now there are even less results in both CIFS and NFS groups, down to 15 for CIFS and 38 for NFS. For any sort of correlation comparison, more results would have better statistical significance.
- In the NFS data, we include some NAS systems which have lots of DRAM cache (almost ~0.5TB). We should probably exclude these as well, which might drop the NFS line down some more (at least lower the B value).
- There are not a lot of enterprise level CIFS systems in current SPECsfs resuslts, with or without SSD or NAND caching. Most CIFS benchmarks are from midrange or lower filers. Unclear why these would do much better on a per spindle basis than a wider sample of NFS systems, but they obviously do.
All that aside, it seems crystal clear here, that CIFS provides more throughput per spindle.
In contrast, we have shown in the past posts how for the limited number of systems that submitted benchmarks with both CIFS and NFS typically show roughly equivalent throughput results for CIFS and NFS. (See my other previous post on this aspect of the CIFS vs. NFS discussion).
Also, in our last post we discussed some of the criticism leveled against this analysis and provided our view to refute these issues. Mostly their concerns are due to the major differences between CIFS state-full protocol and NFS stateless protocol.
But from my perspective it’s all about the data. How quickly can I read a file, how fast can I create a file. Given similar storage systems, with similar SW, cache and hard disk drives, it’s now clear to me that CIFS provides faster access to data than NFS does, at least on a per spindle basis.
Nevertheless, more data may invalidate these results, so stay tuned.
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Why this is should probably be subject for another post but it may have a lot to do with the fact that it is stateless….
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