Disk – Silverton Consulting

GE Research announces new holographic media

Posted on July 28, 2011 by Ray in Data, Data density, Holographic storage

HoloDisc1 (from http://www.gereports.com website)

When last we discussed holographic storage it was over the decline of the industry as a whole and what could be done about it.

Perhaps I posted too soon. GE research just announced that they have come out with a new media formulation offering the possibility of 500GB per single disk platter and broadens the holographic storage ecosystem.

GE also mentioned that there was no need for the holographic storage to be in the form of a disk. InPhase Technologies also had talked of other form factors besides rotating media.

Do rectangular form factors make sense?

Some of these non-disk form factors remind me of the storage cards in StarTrek or memory cards for old programmable electronic calculators. But can they gain any traction?

The only reason a disk makes sense is that with rotating media the heads need only travel in one direction (in an arc with today’s magnetic disks, in an line with today’s CDs and DVD devices) to access a track of data. The rotation of the platter would move all the rest of the data on a track underneath read-write heads.

With a card or any other rectangular form factor, heads and/or media would also need to travel in at least two directions to access data. Of course magnetic tape is a rectangular form factor, and today tape heads move in a single dimension (across the tape width) while the media flows under the heads in an complementary direction, linearly.

So would some form of holographic optical tape make sense. Probably, but the multiple layers needed for holographic storage will require some amount of depth to make it dense enough. Tape’s current volumetric density may be hard to exceed substantially with this multi-layer optical media.

On the other hand, cards could be inserted into a card reader to supply one of these two directions for data access. But this may be hard to do manually at the fine grained track and/or data cell dimensions of today’s data density. Hardware to automatically move the cards down a track of data can certainly be done it just takes technology.

Holographic disks

All that seems to show that disks probably make more sense. The fact that with GE’s new media, holographic disk drives could read/write todays CDs, DVDs, and BlueRay disks would make it much easier to gain market traction.

With GE’s entry into holographic storage they are also possibly looking to use the technology for medical imaging. At the densities being discussed, lots of x-rays, CAT scans, MRI scans, etc. could easily fit on a single piece of holographic media.

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As an industry we have been talking about Holographic storage since the early 90’s. The promise of this technology has always been significant more data per square inch than currently available technologies. But it has been a difficult technology to get to work properly. There’s just a lot of technology that has to be mastered to make it happen, e.g., media, heads, page digitizers, etc.

Nevertheless, holographic storage continues onward.

Comments?

Are SSDs an invasive species?

Posted on January 22, 2010April 10, 2012 by Ray in Market dynamics, Storage, storage economics

A head assembly on a Seagate disk drive by Robert Scoble (cc) (from flickr)

I was reading about pythons becoming an invasive species in the Florida Everglades and that brought to mind SSDs. The current ecological niche in data storage has rotating media as the most prolific predator with tape going on the endangered species list in many locales.

So where does SSD enter into the picture. We have written before on SSD shipments start to take off but that was looking at the numbers from another direction. Given recent announcements it appears that in the enterprise, SSDs seem to be taking over the place formerly held by 15Krpm disk devices. These were formerly the highest performers and most costly storage around. But today, SSDs, as a class of storage, are easily the most costly storage and have the highest performance currently available.

The data

Seagate announced yesterday that they had shipped almost 50M disk drives last quarter up 8% from the prior quarter or ~96M drives over the past 6 months. Now Seagate is not the only enterprise disk provider (Hitachi, Western Digital and others also supply this market) but they probably have the lion’s share. Nonetheless, Seagate did mention that the last quarter was supply constrained and believed that the total addressible market was 160-165M disk drives. That puts Seagate’s market share (in unit volume) at ~31% and at that rate the last 6 months total disk drive production should have been ~312M units.

In contrast, IDC reports that SSD shipments last year totaled 11m units. In both the disk and SSD cases we are not just talking enterprise class devices, the numbers include PC storage as well. If we divide this number in half we have a comparable number of 5.5M SSDs for the last 6 months, giving SSDs less than a 2% market share (in units).

Back to the ecosystem. In the enterprise, there are 15Krpm disks, 10Krpm disks and 7.2Krpm rotating media disks. As speed goes down, capacity goes up. In Seagate’s last annual report they stated that approximately 10% of the drives they manufactured were shipped to the enterprise. Given that rate, of the 312M drives, maybe 31M were enterprise class (this probably overstates the number but usable as an upper bound).

As for SSDs, in the IDC report cited above, they mentioned two primary markets the PC and enterprise markets for SSD penetration. In that same Seagate annual report, they said their desktop and mobile markets were around 80% of disk drives shipped. If we use that proportion for SSDs that would say that of the 5.5M units shipped last half year, 4.4 were in the PC space and 1.1M were for the enterprise. Given that, it would state that the enterprise class SSDs represent ~3.4% of the enterprise class disk drives shipped. This is over 10X more than my prior estimate of SSDs being (<0.2%) of enterprise disk drives. Reality probably lies somewhere between these two estimates.

I wrote a research report a while back which predicted that SSDs would never take off in the enterprise, I was certainly wrong then. If these numbers are correct, capturing 10% of the enterprise disk market in little under 2 years can only mean that high-end, 15Krpm drives are losing ground faster than anticipated. Which brings up the analogy of the invasive species. SSDs seem to be winning a significant beach head in the enterprise market.

In the mean time, drive vendors are fighting back by moving from the 3.5″ to 2.5″ form factor, offering both 15K and 10K rpm drives. This probably means that the 15Krpm 3.5″ drive’s days are numbered.

I made another prediction almost a decade ago that 2.5″ drives would take over the enterprise around 2005 – wrong again, but only by about 5 years or so. I got to stop making predictions, …

7 grand challenges for the next storage century

Posted on November 19, 2009April 10, 2012 by Ray in Data index, Data search, Data security, Market dynamics, Networking, Storage, Storage density, Storage Features, Storage reliability, Strategic Inflection Points

Clock tower (4) by TJ Morris (cc) (from flickr)

I saw a recent IEEE Spectrum article on engineering’s grand challenges for the next century and thought something similar should be done for data storage. So this is a start:

Replace magnetic storage – most predictions show that magnetic disk storage has another 25 years and magnetic tape another decade after that before they run out of steam. Such end-dates have been wrong before but it is unlikely that we will be using disk or tape 50 years from now. Some sort of solid state device seems most probable as the next evolution of storage. I doubt this will be NAND considering its write endurance and other long-term reliability issues but if such issues could be re-solved maybe it could replace magnetic storage.
1000 year storage – paper can be printed today with non-acidic based ink and retain its image for over a 1000 years. Nothing in data storage today can claim much more than a 100 year longevity. The world needs data storage that lasts much longer than 100 years.
Zero energy storage – today SSD/NAND and rotating magnetic media consume energy constantly in order to be accessible. Ultimately, the world needs some sort of storage that only consumes energy when read or written or such storage would provide “online access with offline power consumption”.
Convergent fabrics running divergent protocols – whether it’s ethernet, infiniband, FC, or something new, all fabrics should be able to handle any and all storage (and datacenter) protocols. The internet has become so ubiquitous becauset it handles just about any protocol we throw at it. We need the same or something similar for datacenter fabrics.
Securing data – securing books or paper is relatively straightforward today, just throw them in a vault/safety deposit box. Securing data seems simple but yet is not widely used today. It doesn’t have to be that way. We need better, more long lasting tools and methodology to secure our data.
Public data repositories – libraries exist to provide access to the output of society in the form of books, magazines, papers and other printed artifacts. No such repository exists today for data. Society would be better served if we could store and retrieve data if there were library like institutions could store data. Most of these issues are legal due to data ownership but technological issues exist here as well.
Associative accessed storage – Sequential and random access have been around for over half a century now. Associative storage could complement these and be another approach allowing storage to be retrieved by its content. We can kind of do this today by keywording and indexing data. Biological memory is accessed associations or linkages to other concepts, once accessed memory seem almost sequentially accessed from there. Something comparable to biological memory may be required to build more intelligent machines.

Some of these are already being pursued and yet others receive no interest today. Nonetheless, I believe they all deserve investigation, if storage is to continue to serve its primary role to society, as a long term storehouse for society’s culture, thoughts and deeds.

Comments?

Tape v Disk v SSD v RAM

Posted on July 2, 2009April 10, 2012 by Ray in Market dynamics, Storage, Storage density, Storage performance, Strategy

There was a time not long ago when the title of this post wouldn’t have included SSD. But, with the history of the last couple of years, SSD has earned its right to be included.

A couple of years back I was at a Rocky Mountain Magnetics Seminar (see IEEE magnetics societies) and a disk drive technologist stated that Disks have about another 25 years of technology roadmap ahead of them. During this time they will continue to increase density, throughput and other performance metrics. After 25 years of this they will run up against some theoretical limits which will halt further density progress.

At the same seminar, the presenter said that Tape was lagging Disk technology by about 5-10 years or so. As such, tape should continue to advance for another 5-10 years after disk stops improving at which time tape would also stop increasing density.

Does all this mean the end of tape and disk? I think not. Paper stopped advancing in density theoretically about 2 to 3000 years ago (the papyrus scroll was the ultimate in paper “rotating media”). If we move up to the codex or book form- which in my view is a form factor advance – this took place around 400AD (see history of scroll and codex). Paperback, another form factor advance, took place in the early 20th century (see paperback history).

Turning now to write performance, moveable type was a significant paper (write) performance improvement and started in the mid 15th century. The printing press would go on to improve (paper write) performance for the next six centuries (see printing press history) and continues today.

All this indicates that some data technology, whose density was capped over 2000 years ago, can continue to advance and support valuable activity in today’s world and for the foreseeable future. “Will disk and tape go away” is the wrong question, the right question is “can disk or tape, after SSDs reach price equivalence on a $/GB basis, still be useful to the world”?

I think yes, but that depends on a number of factors as to how the relative SSD-Disk-Tape technologies advance. Assuming someday all these technologies support equivalent Tb/SqIn or spatial density and

SSD’s retain their relative advantage in random access speed,
Tape it’s advantage in sequential throughput, volumetric density, and long media life, and
Disk it’s all around, combined sequential and random access advantage

It seems likely that each can sustain some niche in the data center/home office of tomorrow, although probably not where they are today.

One can see trends being enacted in the enterprise data centers today that are altering the relative positioning of SSDs, disks and tape. Tape is now being relegated to long term, archive storage, Disk is moving to medium-term, secondary storage and SSDs is replacing top tier, primary storage.