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    Q&A – When Compute, Networking and Storage Intersect

    July 18th, 2017

    In Part Vermillion of our SNIA Ethernet Storage Forum (ESF) “Everything You Wanted To Know About Storage But Were Too Proud To Ask” webcast series – we examined the terms and concepts are at the heart of where compute, networking and storage intersect. That’s why we called it “What if Programming and Networking Had a Storage Baby” If you missed the live webcast, you can watch it on-demand.

    The discussion from our panel of experts generated a lot of good questions. As promised, here are answers to them all.

    Q. With regard to persistent memory, how does one decide if it’s better to use load/store or access via I/O?

    A. Legacy applications will not change and hence will access the persistent memory the way they were written. If your legacy application needs a lot of memory and you want to use the new persistent memory as just a big and cheap (volatile) memory, then the access will be byte addressable (load/store). If your legacy application uses block storage then it will use the persistent memory using block addressing. New applications can take advantage of using byte addressing and persistency. They can keep all their data structures in memory, and these data structures will also be persistent! This saves applications the need to serialize before storing and to de-serialize when retrieving from storage and enables many other ways to optimize the software.

    Q. Can you go over again a bit more slowly how byte accessible and LBA change with persistent memory?

    A. Persistent memory can be accessed in three different ways.

    1. Using byte addressing, in which case it behaves like a big (volatile) memory
    2. Using logical block addressing, in which case it behaves like a block storage device
    3. Using SNIA NVM Programming Model that enable byte addressing along with persistency. In this case byte being written into the device can be made persistent with special APIs

    You can configure and decide what model is better use for your application.

    Q. Is that like flash?

    A. Persistent memory is a technology that is persistent like flash, but has byte addressing. It can be implemented using underlying flash, battery backed DRAM, Phase Change Memory and more.

    Q. You were going to parse out flash vs. NVMe, I think. Also, how will the elements discussed during the session impact these evolving technologies?

    A. Flash is a non-volatile memory technology that supports block addressing.

    PCM is another non-volatile technology which is newer that supports byte addressing (which implies that it can also do block addressing by emulation). NVMe describes an interface to access non-volatile memory technology, by placing the non-volatile memory over the PCI bus. Storage Class Memory is yet another interface to access non-volatile memory, by placing the non-volatile memory over the memory bus.

    With this in mind:

    1) It is common to see NVMe devices with backing flash devices. They will support block addressable. They have the option to expose a small byte addressable memory buffer as well on the PCI (typically a DRAM), which may or may not be volatile.

    2) It is common to see Storage Class Memory with backing PCM device, or with DRAM (that can backup itself to flash on power failure). They will support byte addressable.

    Q. Regarding SMB & CIFS protocols, is SMB or CIFS the deprecated one?

    A. The name CIFS hasn’t been used in a while; it’s now all SMB. SMB version1 is deprecated; see this Microsoft article. Don’t use CIFS!

    Q. Are there any rules of thumb in regards to the efficiency of block vs. file vs. object stores from the storage capacity overhead and network “busyness”?

    A. Effectively, as you get closer to the lower-level block storage devices, your storage networking architecture needs to become more deterministic. That is, you begin to start caring more about the number of hosts connecting to a particular storage target (fan-in ratio) and the ratio of bandwidth the target has compared to the bandwidth that the hosts connecting to it have (oversubscription).

    Highly-transactional block storage protocols, such as Fibre Channel, FCoE and lossless iSCSI, for example, will need to have very low oversubscription ratios (sometimes as low as 4:1, depending on the type of application/workload). Most are somewhat more forgiving, and 16:1 and 20:1 are not uncommon. When you move into file-based systems, that oversubscription can be a lot higher (there is no general rule of thumb here, but the oversubscription can be in the low hundreds:1). Object-based systems are so scaled and distributed, that there really are no oversubscription limits at all, because those systems are not highly transactional.

    Q. Does an object always have to be replaced in entirety? How do systems handle updates to large objects?

    A. The rule is that you shouldn’t take a lock on an object. Classically, the whole object should be replaced. Updating is not straightforward.

    Traditional “get/release” locking is too expensive in terms of latency over geographic distances, too hard to manage in a distributed environment, is hard to scale, needs recovery in the case of failure, and introduces state to what is basically storage built for stateless operations. Plus, the object may be sharded across multiple physical systems.

    Some object systems do allow what they call “pessimistic locking” (take a lock for a fixed period of time, say 10 seconds) but it’s not a true lock that you obtain then release. It’s more like a window of opportunity and is often called, and acts like, a lease. There are also other techniques, like “optimistic concurrency” (using a unique identifier, try and then check if your identifier was successful) and “last writer wins” (as it says, the last write is the one that the storage system remembers). Many systems do this by snapshotting the object, allowing updates on the copy, and then atomically swapping them.

    Object systems differ in what they permit. In general, applications need to be aware that they may, very occasionally, not be successful when modifying objects, and to have strategies to deal with it, like retrying or even simply giving up.

    Again, you can check out the recorded version of the webcast at your convenience and you can download the webcasts slides as well if you’d like to follow along. Remember, this webcast was part of series. I encourage you to register today for our next one, which will be on August 1st at 10:00 am PT – Part Turquoise “Where Does My Data Go?” And please visit the SNIA ESF website for our full library of ESF webcasts.


    The Too Proud to Ask Train Makes Another Stop: Where Does My Data Go?

    June 22nd, 2017
    By now, we at the SNIA Storage Ethernet Storage Forum (ESF) hope you are familiar with (perhaps even a loyal fan of) the “Everything You Wanted To Know About Storage But Were Too Proud To Ask,” popular webcast series. On August 1st, the “Too Proud to Ask” train will make another stop. In this seventh session, “Everything You Wanted to Know About Storage But Were Too Proud To Ask: Turquoise – Where Does My Data Go?, we will take a look into the mysticism and magic of what happens when you send your data off into the wilderness. Once you click “save,” for example, where does it actually go?  Continue Reading...

    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.  Continue Reading...

    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...

    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...

    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...

    Would You Like Some Rosé with Your iSCSI?

    February 3rd, 2017

    Would you like some rosé with your iSCSI? I’m guessing that no one has ever asked you that before. But we at the SNIA Ethernet Storage Forum like to get pretty colorful in our “Everything You Wanted To Know about Storage But Were Too Proud To Ask” webcast series as we group common storage terms together by color rather than by number.

    In our next live webcast, Part Rosé – The iSCSI Pod, we will focus entirely on iSCSI, one of the most used technologies in data centers today. With the increasing speeds for Ethernet, the technology is more and more appealing because of its relative low cost to implement. However, like any other storage technology, there is more here than meets the eye.

    We’ve convened a great group of experts from Cisco, Mellanox and NetApp who will start by covering the basic elements to make your life easier if you are considering using iSCSI in your architecture, diving into:

    • iSCSI definition
    • iSCSI offload
    • Host-based iSCSI
    • TCP offload

    Like nearly everything else in storage, there is more here than just a protocol. I hope you’ll register today to join us on March 2nd and learn how to make the most of your iSCSI solution. And while we won’t be able to provide the rosé wine, our panel of experts will be on-hand to answer your questions.

    We’ve Been Thinking…What Does Hyperconverged Mean to Storage?

    February 1st, 2017

    Here at the SNIA Ethernet Storage Forum (ESF), we’ve been discussing how hyperconverged adoption will impact storage. Converged Infrastructure (CI), Hyperconverged Infrastructure (HCI), along with Cluster or Cloud In a Box (CIB) are popular trend topics that have gained both industry and customer adoption. As part of data infrastructures, CI, HCI, and CIB enable simplified deployment of resources (servers, storage, I/O networking, hypervisor, application software) across different environments.

    But what do these approaches mean for the storage environment? What are the key concerns and considerations related specifically to storage? How will the storage be connected to (or included in) the platform? Who will protect and backup the data? And most importantly, how do you know that you’re asking the right questions in order to get to the right answers?

    Find out on March 15th in a live SNIA-ESF webcast, “What Does Hyperconverged Mean to Storage.” We’ve invited expert Greg Schulz, founder and analyst of Server StorageIO, to answer the questions we’ve been debating. Join us, as Greg will move beyond the hype (pun intended) to discuss:

    • What are the storage considerations for CI, CIB and HCI
    • Why fast applications and fast servers need fast I/O
    • Networking and server-storage I/O considerations
    • How to avoid aggravation-causing aggregation (bottlenecks)
    • Aggregated vs. disaggregated vs. hybrid converged
    • Planning, comparing, benchmarking and decision-making
    • Data protection, management and east-west I/O traffic
    • Application and server north-south I/O traffic

    Register today and please bring your questions. We’ll be on-hand to answer them during this event. We hope to see you there!