Zoned Technologies with Western Digital

[Disclosure: I am invited by GestaltIT as a delegate to their Storage Field Day 19 event from Jan 22-24, 2020 in the Silicon Valley USA. My expenses, travel, accommodation and conference fees will be covered by GestaltIT, the organizer and I am not obligated to blog or promote the vendors’ technologies to be presented at this event. The content of this blog is of my own opinions and views]

Storage Field Day 19 is a week away. And one of the vendors presenting is Western Digital, who also presented at Storage Field Day 18 almost a year ago. Here is my blog where I received the full force of Western Digital. In that 10 months or so, Western Digital has sold off their IntelliFlash assets to Data Direct Networks and leaving their ActiveScale object storage platform in limbo.

What is in store from Western D?

I am eager to find out what coming from Western Digital. They have tons of storage technologies that I have yet to encounter, and this anticipation is keeping me excited for the Western D session at Storage Field Day 19.

For a few years I have been keen on a few Western D’s technologies which were moving up the value chain. They are:

• Symbotics Design™ (although I think they changed their marketing messaging)
• OpenFlex architecture, Fabric devices and enclosures
• KingFish™ API for composable infrastructure

In my patch, the signals of the 3 Western D’s technologies have gone weak in the past year. However, there is a lot of momentum right now for Zoned Storage and Zoned Name Space and I believe this could be what is in store for the storage propeller heads like us at Storage Field Day 19.

Zoned Storage for SMR

The voracious demand for larger and larger capacities in hard disk drives has decimated the advancement of CMR (conventional magnetic recording). CMR areal density has pretty much stopped at 1.6 Terabits per inch. SMR (Shingled Magnetic Recording) has been in the market for half a decade and the EAMR (Energy Assisted Magnetic Recording) is entering the market now.  Here is a diagram comparing CMR and SMR.

SMR is all for larger areal densities (about 15-20% more than CMR) by compacting the disk tracks with overlaps. But SMR is poor in terms of write I/O efficiency, with special considerations of rewriting over old data on the overlapped tracks.

To overcome this inefficiency, an amount of leeway and control has to be given away from the disk controllers to the hosts. This was made possible with the advent of new command sets of ZBC (Zoned Block Commands) and ZAC (Zoned-device ATA Commands) defined as ANSI-T1o (SCSI) and -13(ATA) respectively. Both ZBC/ZAC give the host the ability to perform more efficient data placement and thus able to optimize their investment of using SMR drives. This is termed as Host-Managed versus the conventional Drive-Managed SMR. In between both, a superset called Host-Aware SMR was concocted, and is backward compatible with most modern hosts OSes and file systems.

Using the concepts of bands and zones along with ZBC/ZAC command sets, the host is given considerable amount of manageable variables of the SMR drive behaviours, optimizing the drive without compromising drive reliability and data integrity. A perfect example is how Dropbox was able to use host-aware SMR for their Magic Pocket technology.

The Zoned Storage initiative covers the host-aware SMR and also the ZNS (Zoned Name Spaces), a technical proposal from Western Digital as an extension to the NVMe standards.

Zoned Name Spaces

Modern day workloads have changed. They are very diverse, and voluminous and coming at speeds. The deluge of bits, bytes and blocks of these workloads is really magnifying the worst of NAND Flash – poor control of write amplification, over the top over-provisioning, messy garbage collection, tail latency spikes (outliers) and so on.

ZNS (Zoned Name Spaces) is a technical working proposal from Western Digital to the NVMe standards as an extension to align I/O workloads into zones, very similar to the practice of using ZBC/ZAC in SMR drives. Data is written to the zones sequentially (in SMR speak to the respective bands within the zones). If there is a need to overwrite, the pointer of the writer head has to reset to the beginning to rewrite with the new and/or modified data set.

One additional “feature” that SSD can be enhanced with ZNS is parallelism. Instead of using a single write pointer for many zones in SMR, SSD can have many write pointers working in parallel and independently in each zones greatly enhance performance, greater I/O isolation, less locking of CPU cycles. The diagram below shows how zones can be demarcated and parallel I/O for each zones.

If you want further deep drive, check out the video presented by Matias Bjørling, Director of Emerging Systems Architectures of Western Digital.

Zones advantage

The obvious reasons zoning both SMR and SSDs under one initiative – ZonedStorage.io – make a lot of good sense. Storing data will shuffle between the capacity medium (SMR) and the performance medium (SSD), and soon the QLC (Quad Level Cell) medium as well. Putting the management, intelligent data placement and more deterministic performance of the devices, its respective medium and interfaces consolidates the host-level development communicating and interacting with the media beneath it.

This will help the IT industry, the storage networking technology segment to grow and be aligned with the massive requirements from the hyperscalers.

The future is bright but Malaysia?

The IntelliFlash and ActiveScale product set obviously did not fit into the Western Digital strategy, but in my humble opinion, the future remains bright.

I have been an industry pundit here in South East Asia for quite a while, and most prominently in my home country of Malaysia. Western Digital has a strong presence and branding here over the decades. Unfortunately the news of  the closing down the well known manufacturing site in the Sungei Way Free Trade Zone here in Malaysia had tongues wagging, setting the wrong perception about the health of Western Digital overall business.

Less than 5 month ago, just a day before the news of DDN acquiring IntelliFlash, one of the Western Digital new hires called on me. He was previously from Ingram Micro and called me up to introduce Western Digital to me. Sadly the meeting was not up to par, and he spend the whole hour talking about Western D’s hard disk drives, not even the solid state storage. When I asked questions about other Western Digital solutions beyond hard disk drives, there was complete silence. This was degraded further with a partner he brought along, who was smattering about nothing but HDDs. I politely listened to them over the 1 hour meeting but really could not get much value from the whole conversation. Further investigations led me to the Western Digital sales team in Malaysia. They are just not cut out to share Western Digital enterprise solutions that I have endeared to in my industry observations and punditry.

This of course is a gap and an opportunity for Western Digital to be different. Both Seagate and Western D are known for their consumer offerings, and many customers and partners in Malaysia do not address the enterprise market at all. I know that it should be time for Western D to move up to enterprise to gain mind share and branding.

I could be completely wrong.

Storage Field Day 19 is still a week away. I have no idea what they will be presenting but writing this blog is fun (and distracting in a nice way) for me to do some research and learning. I know I will enjoy my trips to the Field Days as always.