20 Questions on SSD #5: Temp, Tier, and Cache + Intel SSD

20 Questions on SSD: Things you’ll want to ask

Question #5: How can I use Temp, Tier, and Cache + Intel SSD?

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So it’s been a few weeks since my last blog and I want to switch gears away from talking about the Intel Data Center Family of SSDs features. We’ve gone over features like production qualification, endurance requirements, power-loss protection, and finally consistent performance. What I want to talk about in this blog is solutions. Specifically, today we have a number options to leverage SSDs without going to the extreme of replacing your hard drives (HDDs) 1-for-1 with SSDs for any particular application.

The solutions team I work in at Intel has spent the last year exploring the benefits of our SSDs in a wide array of environments from Big Data to Virtualization with many stops in-between. The interesting commonality in all of these explorations is that in many cases, the best ROI and TCO benefits come from using the SSD as temp, tier, or cache! There are a few use cases where 1-for-1 replacement of traditional HDDs pays off, but for the most part… repeat after me; temp, tier, and cache... think lions, and tigers, and bears, and a zoo!

In the ‘temp’ space, (wow, that pun was even a stretch for me) we’ve seen goodness in Hadoop with jobs that produce intermediate data by changing the “mapred.local.dir” over to an SSD and with relational databases by moving ‘TempDB’ to a local SSD. In tiering with virtualization, we demonstrated a number of solutions where we built low-cost 100% SSD software based SAN and moved VMs into these high-performance NFS or iSCSI datastores. Using SSDs as buffer/journal/cache, we’ve looked at software based scale-out storage solutions such as VMware’s VSAN, PernixData, Microsoft Storage Spaces, and open source options such as CEPH. In the pure cache space, we’ve also looked at several different caching software packages, including Intel CAS (Cache Acceleration Software), and how these packages can benefit Enterprise IT workloads.

So, there’s plenty of opportunity to leverage SSDs to accelerate your enterprise workloads. The question is, “will your workload benefit enough to yield ROI or a TCO improvement?” Which brings me to my second point, your workload really matters! In my IT past, I often handed off storage workloads to the SAN (Storage Area Network) team. When application performance issues arose; we looked at storage, determined if that was the cause, and requested more IOPS or throughput from the SAN. In contrast, most of the temp, tier, or cache implementations studied by this team focus on locally attached storage or DAS (direct attached storage). This being the case, the application engineer and the systems engineer must work hand-in-hand to look at the workload, details of the IO, and in the case of our testing… determine how to best employ SSDs as temp, tier, cache, or as a final option, complete conversion to SSDs (muahahaha)!

Let me illustrate with a brief walkthrough. Almost 2 years ago now, we published this paper on accelerating database workloads with Intel SSDs. In this paper we did a 1-for1 replacement of local 15k disk drives with SSDs. If we were to repeat this exercise today, we’d need to investigate how much ‘TempDB’ was used, assess whether or not a solution like Intel CAS could help, evaluate features like ‘Buffer Pool Extension’ in Microsoft SQL’14, and then finally look at wholesale replacement of the 15k data drives with SSD based on both the IOP and capacity requirements of the application.

The point here is there are now many more opportunities to realize the benefits inherent in SSDs while keeping capital spend to a minimum. A brief query on one of my favorite retail sites this month (April '14) tells me that a 240GB Intel SSD DC S3500 runs roughly the same price as one of the major OEMs certified 10k SAS drives at 300GB, about $250.00. So in $/GB there’s still a 1.25x difference in cost.

I’m looking forward to the day when by default SSDs are the first choice in local storage and they’re getting close. In fact, for uses like boot/swap the price is close enough to warrant having a RAID 1 SSD solution in-box and an extra Ace in the engineer’s sleeve. Until then, there are a lot of things I can do with temp, tier, and cache. The question for the reader is can you use one of these methods to help your applications and data center run faster while providing a good ROI or decrease in TCO? Could you do more with less and increase efficiency by leveraging SSDs?

- Chris

Christian Black is a Datacenter Solutions Architect covering the HPC and Big Data space within Intel’s Non-Volatile Memory Solutions Group. He comes from a 23 year career in Enterprise IT.

Follow Chris on Twitter at @RekhunSSDs.

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