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    An FAQ to Make Your Storage System Hum

    May 23rd, 2017

    In our most recent “Everything You Wanted To Know About Storage But Were Too Proud To Ask” webcast series – Part Sepia – Getting from Here to There, we discussed terms and concepts that have a profound impact on storage design and performance. If you missed the live event, I encourage you to check it our on-demand. We had many great questions on encapsulation, tunneling, IOPS, latency, jitter and quality of service (QoS). As promised, our experts have gotten together to answer them all.

    Q. Is there a way to measure jitter?

    A. Jitter can be measured directly as a statistical function of the latency, typically as the Variance or Standard Deviation of the latency. For example a storage device might show an average latency of 5ms with a standard deviation of 1.5ms. This means roughly 95% of the transactions have a latency between 2ms and 8ms (average latency plus/minus two standard deviations), however many storage customers measure jitter indirectly by showing the 99.9%, 99.99%, or 99.999% latency. For example if my storage system has 99.99% latency of 8ms, it means 99.99% of transactions have latency <=8ms and 1/10,000 of transactions have latency >8ms. Percentile latency is an indirect measure of jitter but often easier to calculate or understand than the actual jitter.

    Q. Can jitter be easily characterized for storage, media, and networks.  How and what tools are available for doing this?

    A. Jitter is usually easy to measure on a network using standard network monitoring and reporting tools. It may or may not be easy to measure on storage systems or storage media, depending on the tools available (either built-in to the storage OS or using an external management or monitoring tool).  If you can record the latency of each transaction or packet, then it’s easy to calculate and show the jitter using standard statistical measures such as Variance or Standard Deviation of the latency. What most customers do is just measure the 99.9%, 99.99%, or 99.999% latency. This is an indirect measure of jitter but is often much easier to report and understand than the actual jitter.

    Q.  Generally IOPS numbers are published for a particular block size like 8k write/read size, but in reality, IO request per second could be of mixed sizes, what is your perspective on this?

    A. Most IOPS benchmarks test only one I/O size at a time. Most individual real workloads (for example databases) also use only one I/O size.  It is true that a storage controller or HDD/SSD might need to support multiple workloads simultaneously, each with a different I/O size.  While it is possible to run benchmarks with a mix of different I/O sizes, it’s rarely done because then there are too many workload combinations to test and publish. Some storage devices do not perform well if they must handle both small random and large sequential workloads simultaneously, so a smart storage controller might assign different workload types to different disk groups.

    Q. One often misconfigured parameter is queue depth. Can you talk about how this relates to IOPS, latency and jitter?

    A. Queue depth indicates how many tasks or I/Os can be lined up for a particular controller, interface, or CPU. Having a higher queue depth ensures the CPU (or controller or interface) always has a new task to do as soon as it finishes its current task(s). This can result in higher IOPS because the CPU is less likely to have idle time between transactions. But it could also increase latency because the CPU is more likely to be multi-tasking and context switching between different tasks or workloads.

    Q. Can you please repeat all your examples of tunneling? GRE, MPLS, what others? How can it be IPv4 via IPv6?

    A. VXLAN, LISP, GRE, MPLS, IPSEC.  Any time you encapsulate and send one protocol over another and decapsulate at the other end to send the original frame that process is tunneling. In the case we showed of IPv6 over IPv4, you are taking an original IPv6 frame with its IPv6 header of source address to destination address all IPv6 and sending it over and IPv4 enabled network we are encapsulating the IPv6 frame with an IPv4 header and “tunneling” IPv6 over the IPv4 network.

    Q. I think it’d be possible to configure QoS to a point that exceeds the system capacity. Are there any safeguards on avoiding this scenario?

    A. Some types of QoS allow over-provisioning and others do not. For example a QoS that imposes only maximum limits (and no minimum guarantees) on workloads might not prevent many workloads from exceeding system capacity. If the QoS allows over-provisioning, then you should use system monitoring and alerts to warn you when system capacity has been exceeded, or when any workloads are not getting their minimum guaranteed performance.

    Q. Is there any research being done on using storage analytics along with artificial intelligence (AI) to assist with QoS?  

    A. There are a number of storage analytics products, both third party and storage vendor specific that help with QoS. Whether any of these tools may be described as using AI is debatable, since we’re in the early days of using AI to do much in the storage arena. There are many QoS research projects, and no doubt they will eventually make their way into commercially available products if they prove useful.

    Q. Are there any methods (measurements) to calculate IOPS/MBps in tier capable storage? Would it be wrong metric if we estimate based on medium level, example tier 2 (between 1 and 3)?

    A. This question needs refinement, since tiering is sometimes a cache model rather than a data movement model. And knowing the answer may not actually help! Vendors do have tools (normally internal, since they are quite complex) that can help with the planning of tiered storage.

    By now, we hope you’re not “too proud” to ask some of these storage networking questions. We’ve produced four other webcasts in this “Everything You Wanted To Know About Storage,” series to date. They are all available on-demand. And you can register here for our next one on July 6th where we’ll bring in experts to discuss:

    • Storage APIs and POSIX
    • Block, File, and Object storage
    • Byte Addressable and Logical Block Addressing
    • Log Structures and Journaling Systems

    The Ethernet Storage Forum team and I hope to see you there!



    Security and Privacy in the Cloud

    May 22nd, 2017

    When it comes to the cloud, security is always a topic for discussion. Standards organizations like SNIA are in the vanguard of describing cloud concepts and usage, and (as you might expect) are leading on how and where security fits in this new world of dispersed and publicly stored and managed data. On July 20th, the SNIA Cloud Storage Initiative is hosting a live webcast “The State of Cloud Security.” In this webcast, I will be joined by SNIA experts Eric Hibbard and Mark Carlson who will take us through a discussion of existing cloud and emerging technologies, such as the Internet of Things (IoT), Analytics & Big Data, and more, and explain how we’re describing and solving the significant security concerns these technologies are creating. They will discuss emerging ISO/IEC standards, SLA frameworks and security and privacy certifications. This webcast will be of interest to managers and acquirers of cloud storage (whether internal or external), and developers of private and public cloud solutions who want to know more about security and privacy in the cloud.

    Topics covered will include:

    • Summary of the standards developing organization (SDO) activities:
      • Work on cloud concepts, Cloud Data Management Interface (CDMI), an SLA framework, and cloud security and privacy
    • Securing the Cloud Supply Chain:
      • Outsourcing and cloud security, Cloud Certifications (FedRAMP, CSA STAR)
    • Emerging & Related Technologies:
      • Virtualization/Containers, Federation, Big Data/Analytics in the Cloud, IoT and the Cloud

    Register today. We hope to see you on July 20th where Eric, Mark and I will be ready to answer your cloud security questions.

    What if Programming and Networking Had a Storage Baby? Say What?

    May 18th, 2017
    The colorful “Everything You Wanted To Know About Storage But Were Too Proud To Ask,” popular webcast series marches on! In this 6th installment, Part – Vermillion – What if Programming and Networking Had a Storage Baby, we look into some of the nitties and the gritties of storage details that are often assumed. When looking at data from the lens of an application, host, or operating system, it’s easy to forget that there are several layers of abstraction underneath each before the actual placement of data occurs. In this webcast we are going to scratch beyond the first layer to understand some of the basic taxonomies of these layers.  Continue Reading...

    Registration Now Open for Storage Developer Conference India – May 25-26 in Bangalore

    May 15th, 2017

    For the third consecutive year, SNIA will present their highly successful Storage Developer Conference (SDC) in Bangalore, India, on May 25-26, 2017 at the My Fortune Hotel.  The 2017 agenda, developed under the supervision of the SNIA India agenda committee, leads off with a keynote by Indian Institute of Science Professor P. Vijay Kumar on Codes for Big Data:  Error-Correction for Distributed Storage, followed by Amar Tunballi, Engineering Manager at Red Hat, speaking on Software Defined Storage and Why It Will Continue To Be Relevant.  Thursday keynotes will feature Anand Ghatnekar, Country  Continue Reading…

    Too Proud to Ask Webcast Series Continues – Getting from Here to There Pod

    May 4th, 2017
    As part of the SNIA Ethernet Storage Forum’s successful “Everything You Wanted To Know About Storage But Were Too Proud To Ask” series, we’ve discussed numerous topics about storage devices, protocols, and networks. As we examine some of these topics further, we begin to tease out some subtle nuances; subtle, yet important nevertheless. On May 9th we’ll take on the terms and concepts that affect Storage Architectures as a whole in “Everything You Wanted To Know About Storage But Were Too Proud To Ask – Part Sepia – Getting from Here to There.”  Continue Reading...

    SMB3 – These Questions Rock!

    April 24th, 2017
    Earlier this month, the SNIA Ethernet Storage Forum hosted a live webcast on Server Message Block (SMB), “Rockin’ and Rollin’ with SMB3.” Presenting was Ned Pyle, Microsoft SMB Program Manager. If you missed the live event, I encourage you to watch it on-demand. We had a lot of questions from the big audience this event drew, so as promised, here are answers to them all. Q. Other than that audit setup, is there a way to determine, via the OS, which SMB version is in use?  Continue Reading...

    Buffers, Queues and Caches Explained

    April 19th, 2017
    Finely tuning buffers, queues and caches can make your storage system hum. And that’s exactly what we discussed in our recent SNIA Ethernet Storage Forum webcast, ““Everything You Wanted to Know About Storage But Were Too Proud To Ask – Part Teal: The Buffering Pod.” If you missed it, it’s now available on-demand. In this blog, you’ll find detailed answers from our panel of experts to all the great questions we received during the live event. I also encourage you to check out the other on-demand webcasts in this “Too Proud To Ask” series here and stay informed on upcoming events in this series by following us on Twitter @SNIAESF.  Continue Reading...

    Storage Expert Takes on Hyperconverged Questions

    April 17th, 2017
    Last month, we were fortunate enough to have Greg Schulz, analyst and founder of Server Storage IO, as a guest speaker at our SNIA Ethernet Storage Forum webcast, “What Does Hyperconverged Mean to Storage.” If you missed it, it’s now available on-demand. Greg fielded many great questions during the live event, but we didn’t have time to get to them all. So here they are:  Continue Reading...

    Managing Your Computing Ecosystem

    April 12th, 2017

      By George Ericson, Distinguished Engineer, Dell EMC; Member, SNIA Scalable Storage Management Technical Working Group, @GEricson


    This blog is part one of a three-part series recently published on “The Data Cortex”, which represents the thoughts and opinions from members of the CTO Team of Dell EMC’s Data Protection Division.  The author, George Ericson, has been actively participating on the SNIA Scalable Storage Management Technical Working Group which has been developing the SNIA Swordfish storage management specification.  Continue Reading…

    Q&A on All Things iSCSI

    April 7th, 2017
    In the recent SNIA Ethernet Storage Forum iSCSI pod webcast, from our “Everything You Wanted To Know About Storage Part Were Too Proud to Ask” series, we discussed all things iSCSI. If you missed the live event, it’s now available on-demand. As promised, we’ve compiled all the webcast questions with answers from our panel of experts. If you have additional questions, please feel free to ask them in the comment field of this blog. I also encourage you to check out the other on-demand webcasts in this “Too Proud To Ask” series here and stay informed on upcoming events in this series by following us on Twitter @SNIAESF.  Continue Reading...