Tag: IBM DS5300

Latest SPC-2 results – chart of the month

Posted on by Ray in MPBS, SPC-2, Storage, Storage performance, Storage Performance Council, VOD
SPC-2* benchmark results, spider chart for LFP, LDQ and VOD throughput
SPC-2* benchmark results, spider chart for LFP, LDQ and VOD throughput

Latest SPC-2 (Storage Performance Council-2) benchmark resultschart displaying the top ten in aggregate MBPS(TM) broken down into Large File Processing (LFP), Large Database Query (LDQ) and Video On Demand (VOD) throughput results. One problem with this chart is that it really only shows 4 subsystems: HDS and their OEM partner HP; IBM DS5300 and Sun 6780 w/8GFC at RAID 5&6 appear to be the same OEMed subsystem; IBM DS5300 and Sun 6780 w/ 4GFC at RAID 5&6 also appear to be the same OEMed subsystem; and IBM SVC4.2 (with IBM 4700’s behind it).

What’s interesting about this chart is what’s going on at the top end. Both the HDS (#1&2) and IBM SVC (#3) seem to have found some secret sauce for performing better on the LDQ workload or conversely some dumbing down of the other two workloads (LFP and VOD). According to the SPC-2 specification

  • LDQ is a workload consisting of 1024KiB and 64KiB transfers whereas the LFP consists of 1024KiB and 256KiB transfers and the VOD consists of only 256KiB, so transfer size doesn’t tell the whole story.
  • LDQ seems to have a lower write proportion (1%) while attempting to look like joining two tables into one, or scanning data warehouse to create output whereas, LFP processing has a read rate of 50% (R:W of 1:1) while executing a write-only phase, read-write phase and a read-only phase, and apparently VOD has a 100% read only workload mimicking streaming video.
  • 50% of the LDQ workload uses 4 I/Os outstanding and the remainder 1 I/O outstanding. The LFP uses only 1 I/O outstanding and VOD uses only 8 I/Os outstanding.

These seem to be the major differences between the three workloads. I would have to say that some sort of caching sophistication is evident in the HDS and SVC systems that is less present in the remaining systems. And I was hoping to provide some sort of guidance as to what that sophistication looked like but

  • I was going to say they must have a better sequential detection algorithm but the VOD, LDQ and LFP workloads have 100%, 99% and 50% read ratios respectively and sequential detection should perform better with VOD and LDQ than LFP. So thats not all of it.
  • Next I was going to say it had something to do with I/O outstanding counts. But VOD has 8 I/Os outstanding and the LFP only has 1, so the if this were true VOD should perform better than LFP. While LDQ having two sets of phases with 1 and 4 I/Os outstanding should have results somewhere in between these two. So thats not all of it.
  • Next I was going to say stream (or file) size is an important differentiator but “Segment Stream Size” for all workloads is 0.5GiB. So that doesn’t help.

So now I am a complete loss as to understand why the LDQ workloads are so much better than the LFP and VOD workload throughputs for HDS and SVC.

I can only conclude that the little write activity (1%) thrown into the LDQ mix is enough to give the backend storage a breather and allow the subsystem to respond better to the other (99%) read activity. Why this would be so much better for the top performers than the remaining results is not entirely evident. But I would add that, being able to handle lots of writes or lots of reads is relatively straight forward, but handling a un-ballanced mixture is harder to do well.

To validate this conjecture would take some effort. I thought it would be easy to understand what’s happening but as with most performance conundrums the deeper you look the more confounding the results often seem to be.

The full report on the latest SPC results will be up on my website later this year 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.

I will be taking the rest of the week off so Happy Holidays to all my readers and a special thanks to all my commenters. See you next week.

Chart of the month: SPC-1 LRT performance results

Posted on 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 resultsThe 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.