Fast, Safe, Cheap : Pick 3

Today, we're making performance headlines with Oracle's ZFS Storage Appliance.

SPC-1 : Twice the performance of NetApp at the same latency; Half the $/IOPS;

I'm proud to say that, yours truly, along with a lot of great teammates in Oracle, is not totally foreign to this milestone.

We are announcing that Oracle's 7420C cluster acheived 137000 SPC-1 IOPS with an average latency of less than 10 ms. That is double the results of NetApp's 3270A while delivering the same latency. As compared to the NetApp 3270 result, this is a 2.5x improvement in $/SPC-1-IOPS (2.99$/IOPS vs $7.48/IOPS). We're also showing that when the ZFS Storage Appliance runs at the rate posted by the 3270A (68034 SPC-1 IOPS), our latency of 3.26ms is almost 3X lower than theirs (9.16ms). Moreover, our result was obtained with 23700 GB of user level capacity (internally mirrored) for 17.3 $/GB while NetApp's , even using a space saving raid scheme, can only deliver 23.5$/GB. This is the price per GB of application data actually used in the benchmark. On top of that the 7420C still had 40% of space headroom whereas the 3270A was left with only 10% of free blocks.

These great results were at least partly made possible with the availability of 15K RPM Hard Disk Drives (HDD). Those are great to run the most demanding databases because they combine a large IOPS capability and are generally of smaller capacity. The ratio of IOPS/GB makes them ideal to store high intensity database modeled by SPC-1. On top of that, this concerted engineering effort lead to improved software not just for those running on 15K RPM. We actually used this benchmark to seek out how to increase the quality of our products. The preparation runs, after an initial diagnostic of some issue, we were attached to finding solutions that where not targeting the idiosyncrasies of SPC-1 but based on sound design decision. So instead of changing the default value of some internal parameter to a new static default, we actually changed the way the parameter worked so that our storage systems or all types and sizes would benefit.

So not only are we getting a great SPC-1 results, but all existing customers will benefit from this effect even if they are operating outside of the intense conditions created by the benchmark.

So what is SPC-1 ? It is one of the few benchmarks which counts for storage. It is maintained by Storage Performance Council (SPC). SPC-1 simulates multiple databases running on a centralized storage or storage cluster. But even if SPC-1 is a block based benchmark, within the ZFS Storage appliance, a block based FC or iSCSI volume is handled very much the same way as would be a large file subject to synchronous operation. And by Combining modern network technologies (Infiniband or 10Gbe Ethernet), the CPU power packed in the 7420C storage controllers and Oracle's custom dNFS technology for databases, one can truly acheive very high database transaction rates on top of the more manageable and flexible file based protocols.

The benchmarks defines three Application Storage Unit (ASU): ASU1 with a heavy 8KB block read/write component, ASU2 with a much lighter 8KB block read/write component, and ASU3 which is subject to hundreds of write streams. As such it's is not too far from a simulation of running hundreds of Oracle database onto a single system : ASU1 and ASU2 for datafiles and ASU3 for redolog storage.

The total size of the ASUs is constrained such that all of the stored data (including mirror protection and disk used for spares) must exceed 55% of all configured storage. The benchmark team is then free to decide how much total storage to configure. From that figure, 10% is given to ASU3 (redo log space) and the rest divided equally between heavily ASU1 and lightly used ASU2.

The benchmark team also has to select the SPC-1 IOPS throughput level it wishes to run. This is not a light decision given you want to balance high IOPS; low latency and $/user GB.

Once the target IOPS rate is selected, there are multiple criteria needed to pass a successful audit; one of the most critical is that you have to run at the specified IOPS rate for a whole 8 hour. Note that the previous specifications of the benchmark used by NetApp called for an 4 hour run. During that 8 hour run delivering a solid 137000 SPC-1 IOPS, the avg latency of must be less than 30ms (we did much better than that).

After this brutal 8 hour run, the benchmark then enters another critical phase: the workload is restarted (using a new randomly selected working set) and performance is measured for a 10 minute period. It is this 10 minute period that decides the official latency of the run.

When everything is said and done, you press the trigger; go to sleep and wake up to the result. As you could guess we were ecstatic that morning. Before that glorious day, for lack of a stronger word, a lot of hard work had been done during the extensive preparation runs. With little time, and normally not all of the hardware, one runs through series of run at incremental loads, making educated guesses as to how to improve the result. As you get more hardware you scale up the result tweaking things more or less until the final hour.

SPC-1, with it's requirement of less than 45% of unused space, is designed to trigger many disk level random read IOPS. Despite this inherent random pattern of the workload, we saw that our extensive caching architecture was as helpful for this benchmark as it is in real production workloads. While the 15K RPM HDDs normally levels off with random operation at a rate slightly above 300 IOPS, our 7420C, as a whole, could deliver almost 500 user-level SPC-1 IOPS per HDDs.

In the end one of the most satisfying aspect was to see that the data being managed by ZFS was stored rock solid on disk, properly checksummed, all data could be snapshot, compressed on demand, and delivering an impressively steady performance.

2X the absolute performance, 2.5X cheaper per SPC-1 IOPS, almost 3X lower latency, 30% cheaper per user GB with room to grow... So, If you have a storage decision coming and you need, FAST, SAFE, CHEAP : pick 3, take a fresh look at the ZFS Storage appliance.

SPC-1, SPC-1 IOPS, $/SPC-1 IOPS reg tm of Storage Performance Council (SPC). More info Sun ZFS Storage 7420 Appliance and

Oracle Sun ZFS Storage Appliance 7420 _ _As of October 3, 2011 Netapp FAS3270A _ _As of October 3, 2011

The views expressed on this blog are my own and do not necessarily reflect the views of Oracle.


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