The adjacent chart is from our September newsletter and shows the top 10 NFSv3 throughput results from the latest SPEC(R) sfs2008 benchmark runs published as of 25 September 2009.
There have been a number of recent announcements of newer SPECsfs2008 results in the news of late, namely Symantec’s FileStore and Avere Systems releases but these results are not covered here. In this chart, the winner is the NetApp FAS6080 with FCAL disks behind it, clocking in at 120K NFSv3 operations/second. This was accomplished with 324 disk drives using 2-10Gbe links.
PAM comes out
All that’s interesting of course but what is even more interesting is NetApp’s results with their PAM II (Performance Accelerator Module) cards. The number 3, 4 and 5 results were all with the same system (FAS3160) with different configurations of disks and PAM II cards. Specifically,
- The #3 result had a FAS3160, running 56 FCAL disks with PAM II cards and DRAM cache of 532GBs. The system attained 60.5K NFSv3 operations per second.
- The #4 result had a FAS3160, running 224 FCAL disks with no PAM II cards but 20GB of DRAM cache. This system attained 60.4K NFSv3 ops/second.
- The #5 result had a FAS3160, running 96 SATA disks with PAM II cards and DRAM cache of 532GBs. This system also attained 60.4K NFSv3 ops/second.
Similar results can be seen with the FAS3140 systems at #8, 9 and 10. In this case the FAS3140 systems were using PAM I (non-NAND) cards with 41GB of cache for results #9 and 10, while #8 result had no PAM with only 9GB of Cache. The #8 result used 224 FCAL disks, #9 used 112 FCAL disks, and #10 had 112 SATA disks. They were able to achieve 40.1K, 40.1K and 40.0K NFSv3 ops/second respectively.
Don’t know how much PAM II cards cost versus FCAL or SATA disks but there is an obvious trade off here. You can use less FCAL or cheaper SATA disks but attain the same NFSv3 ops/second performance.
As I understand it, the PAM II cards come in 256GB configurations and you can have 1 or 2 cards in a FAS system configuration. PAM cards act as an extension of FAS system cache and all IO workloads can benefit from their performance.
As with all NAND flash, write access is significantly slower than read and NAND chip reliability has to be actively managed through wear leveling and other mechanisms to create a reliable storage environment. We assume either NetApp has implemented the appropriate logic to support reliable NAND storage or has purchased NAND cache with the logic already onboard. In any case, the reliability of NAND is more concerned with write activity than read and by managing the PAM cache to minimize writes, NAND reliability concerns could easily be avoided.
The full report on the latest SPECsfs2008 results will be up on my website later this week but if you want to get this information earlier and receive your own copy of our newsletter – email me at SubscribeNews@SilvertonConsulting.com?Subject=Subscribe_to_Newsletter.
Full disclosure: I currently have a contract with NetApp on another facet of their storage but it is not on PAM or NFSv3 performance.