TMS RamSan – Silverton Consulting

Has latency become the key metric? SPC-1 LRT results – chart of the month

Posted on July 16, 2013 by Ray in Block Storage, Disk storage, LRT, SPC-1, SSD storage, Storage, Storage performance, Storage Performance Council

I was at EMCworld a couple of months back and they were showing off a preview of the next version VNX storage, which was trying to achieve a million IOPS with under a millisecond latency. Then I attended NetApp’s analyst summit and the discussion at their Flash seminar was how latency was changing the landscape of data storage and how flash latencies were going to enable totally new applications.

One executive at NetApp mentioned that IOPS was never the real problem. As an example, he mentioned one large oil & gas firm that had a peak IOPS of 35K.

Also, there was some discussion at NetApp of trying to come up with a way of segmenting customer applications by latency requirements. Aside from high frequency trading applications, online payment processing and a few other high-performance database activities, there wasn’t a lot that could easily be identified/quantified today.

IO latencies have been coming down for years now. Sophisticated disk only storage systems have been lowering latencies for over a decade or more. But since the introduction of SSDs it’s been a whole new ballgame. For proof all one has to do is examine the top 10 SPC-1 LRT (least response time, measured with workloads@10% of peak activity) results.

In looking over the top 10 SPC-1 LRT benchmarks (see Figure above) one can see a general pattern. These systems mostly use SSD or flash storage except for TMS-400, TMS 320 (IBM FlashSystems) and Kaminario’s K2-D which primarily use DRAM storage and backup storage.

Hybrid disk-flash systems seem to start with an LRT of around 0.9 msec (not on the chart above). These can be found with DotHill, NetApp, and IBM.

Similarly, you almost have to get to as “slow” as 0.93 msec. before you can find any disk only storage systems. But most disk only storage comes with a latency at 1msec or more. Between 1 and 2msec. LRT we see storage from EMC, HDS, HP, Fujitsu, IBM NetApp and others.

There was a time when the storage world was convinced that to get really good response times you had to have a purpose built storage system like TMS or Kaminario or stripped down functionality like IBM’s Power 595. But it seems that the general purpose HDS HUS, IBM Storwize, and even Huawei OceanStore are all capable of providing excellent latencies with all SSD storage behind them. And all seem to do at least in the same ballpark as the purpose built, TMS RAMSAN-620 SSD storage system. These general purpose storage systems have just about every advanced feature imaginable with the exception of mainframe attach.

It seems nowadays that there is a trifurcation of latency results going on, based on underlying storage:

DRAM only systems at 0.4 msec to ~0.1 msec.
SSD/flash only storage at 0.7 down to 0.2msec
Disk only storage at 0.93msec and above.

The hybrid storage systems are attempting to mix the economics of disk with the speed of flash storage and seem to be contending with all these single technology, storage solutions.

It’s a new IO latency world today. SSD only storage systems are now available from every major storage vendor and many of them are showing pretty impressive latencies. Now with fully functional storage latency below 0.5msec., what’s the next hurdle for IT.

Comments?

Image: EAB 2006 by TMWolf

SPC-1 Results IOPs vs. Capacity – chart of the month

Posted on March 23, 2010October 8, 2012 by Ray in IOPS, SPC-1, Storage, Storage performance, Storage Performance Council

SPC-1* IOPS vs. Capacity, (c) 2010 Silverton Consuliting, All Rights Reserved

This chart is from SCI’s last months report on recent Storage Performance Council (SPC) benchmark results. There were a couple of new entries this quarter but we decided to introduce this new chart as well.

This is a bubble scatter plot of SPC-1(TM) (online transaction workloads) results. Only storage subsystems that cost less than $100/GB, trying to introduce some fairness.

Bubble size is a function of the total cost of the subsystem
Horizontal access is subsystem capacity in GB
Vertical access is peak SPC-1 IOPS(TM)

Also we decided to show a linear regression line and equation to better analyze the data. As shown in the chart there is a pretty good correlation between capacity and IOPS (R**2 of ~0.8). The equation parameters can be read from the chart but it seems pretty tight from a visual perspective.

The one significant outlier here at ~250K IOPS is TMS RAMSAN which uses SSD technology. The two large bubbles at the top right were two IBM SVC 5.1 runs at similar backend capacity. The top SVC run had 6 nodes and the bottom SVC run only had 4.

As always, a number of caveats to this:

Not all subsystems on the market today are benchmarked with SPC-1
The pricing cap eliminated high priced storage from this analysis
IOPS may or may not be similar to your workloads.

Nevertheless, most storage professionals come to realize that having more disks can often result in better performance. This is often confounded by RAID type used, disk drive performance, and cache size. However, the nice thing about SPC-1 runs, is that most (nearly all) use RAID 1, have the largest cache size that makes sense, and the best performing disk drives (or SSDs). The conclusion cannot be more certain – the more RAID 1 capacity one has the higher the number of IOPS one can attain from a given subsystem.

The full SPC report went out to our newsletter subscribers last month and a copy of the report will be up on the dispatches page of our website later this month. However, you can get this information now and subscribe to future newsletters to receive future full reports even earlier, just email us at SubscribeNews@SilvertonConsulting.com?Subject=Subscribe_to_Newsletter.

As always, we welcome any suggestions on how to improve our analysis of SPC or any of our other storage system performance results. This new chart was a result of one such suggestion.

Chart of the month: SPC-1 LRT performance results

Posted on September 17, 2009October 8, 2012 by Ray in Data security, LRT, SPC-1, Storage, Storage Features, Storage performance, Storage Performance Council, Systems

Chart of the Month: SPC-1 LRT(tm) performance results The above chart shows the top 12 LRT(tm) (least response time) results for Storage Performance Council’s SPC-1 benchmark. The vertical axis is the LRT in milliseconds (msec.) for the top benchmark runs. As can be seen the two subsystems from TMS (RamSan400 and RamSan320) dominate this category with LRTs significantly less than 2.5msec. IBM DS8300 and it’s turbo cousin come in next followed by a slew of others.

The 1msec. barrier

Aside from the blistering LRT from the TMS systems one significant item in the chart above is that the two IBM DS8300 systems crack the <1msec. barrier using rotating media. Didn’t think I would ever see the day, of course this happened 3 or more years ago. Still it’s kind of interesting that there haven’t been more vendors with subsystems that can achieve this.

LRT is probably most useful for high cache hit workloads. For these workloads the data comes directly out of cache and the only thing between a server and it’s data is subsystem IO overhead, measured here as LRT.

Encryption cheap and fast?

The other interesting tidbit from the chart is that the DS5300 with full drive encryption (FDE), (drives which I believe come from Seagate) cracks into the top 12 at 1.8msec exactly equivalent with the IBM DS5300 without FDE. Now FDE from Seagate is a hardware drive encryption capability and might not be measurable at a subsystem level. Nonetheless, it shows that having data security need not reduce performance.

What is not shown in the above chart is that adding FDE to the base subsystem only cost an additional US$10K (base DS5300 listed at US$722K and FDE version at US$732K). Seems like a small price to pay for data security which in this case is simply turn it on, generate keys, and forget it.

FDE is a hard drive feature where the drive itself encrypts all data written and decrypts all data read to from a drive and requires a subsystem supplied drive key at power on/reset. In this way the data is never in plaintext on the drive itself. If the drive were taken out of the subsystem and attached to a drive tester all one would see is ciphertext. Similar capabilities have been available in enterprise and SMB tape drives is the past but to my knowledge the IBM DS5300 FDE is the first disk storage benchmark with drive encryption.

I believe the key manager for the DS5300 FDE is integrated within the subsystem. Most shops would need a separate, standalone key manager for more extensive data security. I believe the DS5300 can also interface with an standalone (IBM) key manager. In any event, it’s still an easy and simple step towards increased data security for a data center.

The full report on the latest SPC 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.