The future of Fibre Channel in the Cloud Era

The world has pretty much settled that hybrid cloud is the way to go for IT infrastructure services today. Straddled between the enterprise data center and the infrastructure-as-a-service in public cloud offerings, hybrid clouds define the storage ecosystems and architecture of choice.

A recent Blocks & Files article, “Broadcom server-storage connectivity sales down but recovery coming” caught my attention. One segment mentioned that the server-storage connectivity sales was down 9% leading me to think “Is this a blip or is it a signal that Fibre Channel, the venerable SAN (storage area network) protocol is on the wane?

Fibre Channel Sign

Thus, I am pondering the position of Fibre Channel SANs in the cloud era. Where does it stand now and in the near future? Continue reading

RAIDZ expansion and dRAID excellent OpenZFS adventure

RAID (Redundant Array of Independent Disks) is the foundation of almost every enterprise storage array in existence. Thus a technology change to a RAID implementation is a big deal. In recent weeks, we have witnessed not one, but two seismic development updates to the volume management RAID subsystem of the OpenZFS open source storage platform.

OpenZFS logo

For the uninformed, ZFS is one of the rarities in the storage industry which combines the volume manager and the file system as one. Unlike traditional volume management, ZFS merges both the physical data storage representations (eg. Hard Disk Drives, Solid State Drives) and the logical data structures (eg. RAID stripe, mirror, Z1, Z2, Z3) together with a highly reliable file system that scales. For a storage practitioner like me, working with ZFS is that there is always a “I get it!” moment every time, because the beauty is there are both elegances of power and simplicity rolled into one.

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Blasphemous technical writing

This is so, so, so wrong! I want to hold back but I can’t hold back no more!

This article from Petapixel appeared in my daily news feed last week. When I saw the title “Seagate performed best in Backblaze’s 2020 Hard Drive Failure Report“, I literally jumped. My immediate thoughts were “This can’t be right“.

Labelling Seagate as the best performer in a Backblaze report not only sounded oxymoronic. It was moronic. For those of us who have the industry experience, we know enough that this cannot be true with just a one fell swoop statement.

Petapixel misleading article title

Backblaze report

Backblaze has been releasing Hard Drive Stats and Report every quarter since 2013. For many of us practitioners, the report has been the de facto standard and indicator of hard disks reliability. Inadvertently, it defines the quality of the hard disk drives associated with the respective manufacturer’s brand and models.

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Layers in Storage – For better or worse

Storage arrays and storage services are built upon by layers and layers beneath its architecture. The physical components of hard disk drives and solid states are abstracted into RAID volumes, virtualized into other storage constructs before they are exposed as shares/exports, LUNs or objects to the network.

Everyone in the storage networking industry, is cognizant of the layers and it is the foundation of knowledge and experience. The public cloud storage services side is the same, albeit more opaque. Nevertheless, both have layers.

In the early 2000s, SNIA® Technical Council outlined a blueprint of the SNIA® Shared Storage Model, a framework describing layers and properties of a storage system and its services. It was similar to the OSI 7-layer model for networking. The framework helped many industry professionals and practitioners shaped their understanding and the development of knowledge in their respective fields. The layering scheme of the SNIA® Shared Storage Model is shown below:

SNIA Shared Storage Model – The layering scheme

Storage vendors layering scheme

While SNIA® storage layers were generic and open, each storage vendor had their own proprietary implementation of storage layers. Some of these architectures are simple, but some, I find a bit too complex and convoluted.

Here is an example of the layers of the Automated Volume Management (AVM) architecture of the EMC® Celerra®.

EMC Celerra AVM Layering Scheme

I would often scratch my head about AVM. Disks were grouped into RAID groups, which are LUNs (Logical Unit Numbers). Then they were defined as Celerra® dvols (disk volumes), and stripes of the dvols were consolidated into a storage pool.

From the pool, a piece of a storage capacity construct, called a slice volume, were combined with other slice volumes into a metavolume which eventually was presented as a file system to the network and their respective NAS clients. Explaining this took an effort because I was the IP Storage product manager for EMC® between 2007 – 2009. It was a far cry from the simplicity of NetApp® ONTAP 7 architecture of RAID groups and volumes, and the WAFL® (Write Anywhere File Layout) filesystem.

Another complicated layered framework I often gripe about is Ceph. Here is a look of how the layers of CephFS is constructed.

Ceph Storage Layered Framework

I work with the OpenZFS filesystem a lot. It is something I am rather familiar with, and the layered structure of the ZFS filesystem is essentially simpler.

Storage architecture mixology

Engineers are bizarre when they get too creative. They have a can do attitude that transcends the boundaries of practicality sometimes, and boggles many minds. This is what happens when they have their own mixology ideas.

Recently I spoke to two magnanimous persons who had the idea of providing Ceph iSCSI LUNs to the ZFS filesystem in order to use the simplicity of NAS file sharing capabilities in TrueNAS® CORE. From their own words, Ceph NAS capabilities sucked. I had to draw their whole idea out in a Powerpoint and this is the architecture I got from the conversation.

There are 3 different storage subsystems here just to provide NAS. As if Ceph layers aren’t complicated enough, the iSCSI LUNs from Ceph are presented as Cinder volumes to the KVM hypervisor (or VMware® ESXi) through the Cinder driver. Cinder is the persistent storage volume subsystem of the Openstack® project. The Cinder volumes/hypervisor datastore are virtualized as vdisks to the respective VMs installed with TrueNAS® CORE and OpenZFS filesystem. From the TrueNAS® CORE, shares and exports are provisioned via the SMB and NFS protocols to Windows and Linux respectively.

It works! As I was told, it worked!

A.P.P.A.R.M.S.C. considerations

Continuing from the layered framework described above for NAS, other aspects beside the technical work have to be considered, even when it can work technically.

I often use a set of diligent data storage focal points when considering a good storage design and implementation. This is the A.P.P.A.R.M.S.C. Take for instance Protection as one of the points and snapshot is the technology to use.

Snapshots can be executed at the ZFS level on the TrueNAS® CORE subsystem. Snapshots can be trigged at the volume level in Openstack® subsystem and likewise, rbd snapshots at the Ceph subsystem. The question is, which snapshot at which storage subsystem is the most valuable to the operations and business? Do you run all 3 snapshots? How do you execute them in succession in a scheduled policy?

In terms of performance, can it truly maximize its potential? Can it churn out the best IOPS, and deliver at wire speed? What is the latency we can expect with so many layers from 3 different storage subsystems?

And supporting this said architecture would be a nightmare. Where do you even start the troubleshooting?

Those are just a few considerations and questions to think about when such a layered storage architecture along. IMHO, such a design was over-engineered. I was tempted to say “Just because you can, doesn’t mean you should

Elegance in Simplicity

Einstein (I think) quoted:

Einstein’s quote on simplicity and complexity

I am not saying that having too many layers is wrong. Having a heavily layered architecture works for many storage solutions out there, where they are often masked with a simple and intuitive UI. But in yours truly point of view, as a storage architecture enthusiast and connoisseur, there is beauty and elegance in simple designs.

The purpose here is to promote better understanding of the storage layers, and how they integrate and interact with each other to deliver the data services to the network. In the end, that is how most storage architectures are built.

 

Do we still need FAST (and its cohorts)?

In a recent conversation with an iXsystems™ reseller in Hong Kong, the topic of Storage Tiering was brought up. We went about our banter and I brought up the inter-array tiering and the intra-array tiering piece.

After that conversation, I started thinking a lot about intra-array tiering, where data blocks within the storage array were moved between fast and slow storage media. The general policy was simple. Find all the least frequently access blocks and move them from a fast tier like the SSD tier, to a slower tier like the spinning drives with different RPM speeds. And then promote the data blocks to the faster media when accessed frequently. Of course, there were other variables in the mix besides storage media and speeds.

My mind raced back 10 years or more to my first encounter with Compellent and 3PAR. Both were still independent companies then, and I had my first taste of intra-array tiering

The original Compellent and 3PAR logos

I couldn’t recall which encounter I had first, but I remembered the time of both events were close. I was at Impact Business Solutions in their office listening to their Compellent pitch. The Kuching boys (thank you Chyr and Winston!) were very passionate in evangelizing the Compellent Data Progression technology.

At about the same time, I was invited by PTC Singapore GM at the time, Ken Chua to grace their new Malaysian office and listen to their latest storage vendor partnership, 3PAR. I have known Ken through my NetApp® days, and he linked me up Nathan Boeger, 3PAR’s pre-sales consultant. 3PAR had their Adaptive Optimization (AO) disk tiering and Dynamic Optimization (DO) technology.

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Discovering OpenZFS Fusion Pool

Fusion Pool excites me, but unfortunately this new key feature of OpenZFS is hardly talked about. I would like to introduce the Fusion Pool feature as iXsystems™ expands the TrueNAS® Enterprise storage conversations.

I would not say that this technology is revolutionary. Other vendors already have the similar concept of Fusion Pool. The most notable (to me) is NetApp® Flash Pool, and I am sure other enterprise storage vendors have the same. But this is a big deal (for me) for an open source file system in OpenZFS.

What is Fusion Pool  (aka ZFS Allocation Classes)?

To understand Fusion Pool, we have to understand the basics of the ZFS zpool. A zpool is the aggregation (borrowing the NetApp® terminology) of vdevs (virtual devices), and vdevs are a collection of physical drives configured with the OpenZFS RAID levels (RAID-0, RAID-1, RAID-Z1, RAID-Z2, RAID-Z3 and a few nested RAID permutations). A zpool can start with one vdev, and new vdevs can be added on-the-fly, expanding the capacity of the zpool online.

There are several types of vdevs prior to Fusion Pool, and this is as of pre-TrueNAS® version 12.0. As shown below, these are the types of vdevs available to the zpool at present.

OpenZFS zpool and vdev types – Credit: Jim Salter and Arstechnica

Fusion Pool is a zpool that integrates with a new, special type of vdev, alongside other normal vdevs. This special vdev is designed to work with small data blocks between 4-16K, and is highly efficient in handling random reading and writing of these small blocks. This bodes well with the OpenZFS file system metadata blocks and other blocks of small files. And the random nature of the Read/Write I/Os works best with SSDs (can be read or write intensive SSDs).

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OpenZFS 2.0 exciting new future

The OpenZFS (virtual) Developer Summit ended over a weekend ago. I stayed up a bit (not much) to listen to some of the talks because it started midnight my time, and ran till 5am on the first day, and 2am on the second day. Like a giddy schoolboy, I was excited, not because I am working for iXsystems™ now, but I have been a fan and a follower of the ZFS file system for a long time.

History wise, ZFS was conceived at Sun Microsystems in 2005. I started working on ZFS reselling Nexenta in 2009 (my first venture into business with my company nextIQ) after I was professionally released by EMC early that year. I bought a Sun X4150 from one of Sun’s distributors, and started creating a lab server. I didn’t like the workings of NexentaStor (and NexentaCore) very much, and it was priced at 8TB per increment. Later, I started my second company with a partner and it was him who showed me the elegance and beauty of ZFS through the command lines. The creed of ZFS as a volume and a file system at the same time with the CLI had an effect on me. I was in love.

OpenZFS Developer Summit 2020 Logo

OpenZFS Developer Summit 2020 Logo

Exciting developments

Among the many talks shared in the OpenZFS Developer Summit 2020 , there were a few ideas and developments which were exciting to me. Here are 3 which I liked and I provide some commentary about them.

  • Block Reference Table
  • dRAID (declustered RAID)
  • Persistent L2ARC

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Intel is still a formidable force

It is easy to kick someone who is down. Bad news have stronger ripple effects than the good ones. Intel® is going through a rough patch, and perhaps the worst one so far. They delayed their 7nm manufacturing process, one which could have given Intel® the breathing room in the CPU war with rival AMD. And this delay has been pushed back to 2021, possibly 2022.

Intel Apple Collaboration and Partnership started in 2005

Their association with Apple® is coming to an end after 15 years, and more security flaws surfaced after the Spectre and Meltdown debacle. Extremetech probably said it best (or worst) last month:

If we look deeper (and I am sure you have), all these negative news were related to their processors. Intel® is much, much more than that.

Their Optane™ storage prowess

I have years of association with the folks at Intel® here in Malaysia dating back 20 years. And I hardly see Intel® beating it own drums when it comes to storage technologies but they are beginning to. The Optane™ revolution in storage, has been a game changer. Optane™ enables the implementation of persistent memory or storage class memory, a performance tier that sits between DRAM and the SSD. The speed and more notable the latency of Optane™ are several times faster than the Enterprise SSDs.

Intel pyramid of tiers of storage medium

If you want to know more about Optane™’s latency and speed, here is a very geeky article from Intel®:

The list of storage vendors who have embedded Intel® Optane™ into their gears is long. Vast Data, StorOne™, NetApp® MAX Data, Pure Storage® DirectMemory Modules, HPE 3PAR and Nimble Storage, Dell Technologies PowerMax, PowerScale, PowerScale and many more, cement Intel® storage prowess with Optane™.

3D Xpoint, the Phase Change Memory technology behind Optane™ was from the joint venture between Intel® and Micron®. That partnership was dissolved in 2019, but it has not diminished the momentum of next generation Optane™. Alder Stream and Barlow Pass are going to be Gen-2 SSD and Persistent Memory DC DIMM respectively. A screenshot of the Optane™ roadmap appeared in Blocks & Files last week.

Intel next generation Optane roadmap

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Falconstor Software Defined Data Preservation for the Next Generation

Falconstor® Software is gaining momentum. Given its arduous climb back to the fore, it is beginning to soar again.

Tape technology and Digital Data Preservation

I mentioned that long term digital data preservation is a segment within the data lifecycle which has merits and prominence. SNIA® has proved that this is a strong growing market segment through its 2007 and 2017 “100 Year Archive” surveys, respectively. 3 critical challenges of this long, long-term digital data preservation is to keep the archives

  • Accessible
  • Undamaged
  • Usable

For the longest time, tape technology has been the king of the hill for digital data preservation. The technology is cheap, mature, and many enterprises has built their long term strategy around it. And the pulse in the tape technology market is still very healthy.

The challenges of tape remain. Every 5 years or so, companies have to consider moving the data on the existing tape technology to the next generation. It is widely known that LTO can read tapes of the previous 2 generations, and write to it a generation before. The tape transcription process of migrating digital data for the sake of data preservation is bad because it affects the structural integrity and quality of the content of the data.

In my times covering the Oil & Gas subsurface data management, I have seen NOCs (national oil companies) with 500,000 tapes of all generations, from 1/2″ to DDS, DAT to SDLT, 3590 to LTO 1-7. And millions are spent to transcribe these tapes every few years and we have folks like Katalyst DM, Troika and more hovering this landscape for their fill.

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