Tag Archives: Drives

Data Storage War: Flash Vs. Hard Drives

The struggle for market share between flash-based drives and hard-disk drives is so similar to physical conflict that we can apply the same language. Wars are essentially territorial, with outcomes determined by who owns the battlefield. Logistics chains and technological leadership often determine point battles and having superiority of resources is always a major factor in sustaining an attack.

We often see the flash/HDD battle portrayed as a cloudy whole, forgetting that there are in fact a series of battlefronts. The devil is in the details and a map of the storage world today shows how, insidiously, flash-based products have gained almost all the available territory.

Storage today ranges from small drives used in medical and industrial gear to super-fast all-flash arrays that deliver millions of I/O operations per second. Factors such as weight, physical size, and power help determine the best storage match, together with price and performance. Logistics — for example, the availability of component die — are a major factor in setting storage prices and thus the balance of competitiveness.

To complicate issues, however, flash and HDDs are miles apart when it comes to performance. Using a solid-state drive may make a server run three or more times faster than the same configuration using HDDs. This is the technology component of the battlefront. Many comparisons of HDD and SSD prices ignore the impact of the difference on overall TCO, so consequently they overstate the cost of SSD-based solutions. This oversight has slowed SSD sales for years, though the industry today has mostly savvied up.

As we fly over the storage drive battlefields, what do we see? SSDs have established total technological dominance in most areas. For example, 15K and 10K RPM hard drives are topped out and starved of future investment; they just can’t keep up with SSDs and they cost more. This concedes the enterprise drive space to SSDs, with a resulting decline in RAID arrays and SAN gear. It’s interesting that SANs aren’t surrendering yet, but I’ll touch on that later.

The mobile PC space faces a race to the bottom, which has forced vendors to enrich configurations to make any margin. An obvious play is to go all-flash, implying longer battery life and less weight, among other benefits. SSDs now own most of this territory.

As we go territory by territory, we see that flash has won or is winning handily. The one exception is nearline bulk storage, where top hard-disk drive vendor Seagate, projects 10 more years of HDD dominance in bulk storage. I don’t buy that story and you’ll see why in this slideshow!

Note that battles may be won, but storage is a conservative market and change takes years. Businesses are still buying 15 K hard drives and nearline SATA drives won’t go away overnight!

(Image: Satakorn/Shutterstock)

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Hard Disk Drives Cling to Life as SSDs Take Off

Despite recent developments in hard-disk drive technology, solid-state drives are on the way to becoming the solution of choice for enterprise storage. They have cost more than HDDs, which held back adoption considerably for the last few years, but the situation changed this year, as I predicted.

The secondary storage market is characterized as using high-capacity 3.5 inch hard drives. The segment is price-sensitive rather than performance oriented and, due to hard-drive capacity growth over the last half-decade, remains the primary market for HDDs.

The HDD capacity growth curve has, however, stalled out. Moving beyond 14TB – the capacity Western Digital announced in October and the largest HDD to date — will prove difficult technically. The common approach to larger capacity has been Heat-Assisted Magnetic Recording (HAMR), where a laser is used to magnetically “soften” the area to write a bit. Vendors promise to reach 100TB capacity in eight years, for example, but the technology is very difficult to get right, never mind produce in volume.

WD said it’s using an alternative approach, MAMR, which uses microwaves to achieve softening. The company promises to ship its first MAMR product in 2019, which may prove a bit optimistic. The problem with either approach is that we already have 32TB SSDs, which fit in a smaller 2.5 inch footprint, effectively half the size of these bulk HDDs.

The evolution of SSD capacity is moving rapidly along with 3D NAND, die stacking, and QLC cell architectures all poised to drop prices rapidly in 2018 and to make even larger capacities available. We can certainly expect 64TB SSDs in 2018 and perhaps even see the 100TB units several vendors have promised.

These large SSDs will likely be at a dollars/terabyte premium over HDDs for a while, but the capacity increase and reduced size means many fewer appliances will be needed to store secondary, cold, data. Moreover, non-traditional drive packaging such as Intel’s elongated M2 blades, with 32 blades of 32TB each in a 1U appliance, promise 5PB in a 1U appliance when combined with compression.

Already this year, perceptions around SSD costs have been impacted by a realization that the much greater throughput possible with SSD primary storage means that fewer servers are needed to run a given workload, with the resulting savings more than offsetting extra pricing for the drives. Also, the cost of NVMe flash drives has moved close to SAS and SATA pricing, resulting in NVMe now being the interface of choice in servers and even desktops.

At the same time, SSD-based all-flash arrays (AFAs) have displaced the RAID array as the preferred approach in networked storage. Here, because of the high bandwidth available, AFAs support compression of both the primary data they store and the secondary data stream being offloaded to other storage appliances. For most applications, compression results in a 5:1 effective multiplication of the raw capacity. Because HDD primary storage is way too slow, compression is not a viable option for RAID arrays.

A third trend benefiting SSDs is the growth of hyperconverged infrastructure. Based originally on SSDs, HCI has migrated to NVMe SSDs to obtain the response times and throughput those drives bring. Led by Excelero, the next step in HCI is direct connection of NVMe drives to the RDMA Ethernet fabric of the cluster of nodes, removing latency and providing very high throughput. Excelero’s approach opens up directly connecting future NVMe Ethernet drives to the cluster fabric, allowing a great deal of parallelism in the cluster storage design.

The result of all of these trends is that this year the battle for market share is heating up, with SSD pulling ahead strongly in the enterprise drive class. At the same time, SAN-based primary storage is in decline, with RAID array sales falling quarter by quarter.

Can desktops hold the HDD market up for a while? I just bought a new system, with a mid-market motherboard. It has four slots for M2 NVMe SSDs! Gamers will generally go for speed, especially more so when the price of the NVMe drive is identical to the SATA equivalent!

One bump in the road for SSDs is flash die production capacity. The conversion to 3D NAND was more difficult for suppliers than expected, causing shortages in the first half of this year. With that problem moving into the history column and real capacity gains from the recent innovation of die stacking  for 3D NAND, 2018 will see supply moving close to demand. Still, demand will be high for NAND die so shortages may persist during the transition from HDDs.

With few factors in their favor, hard drives are looking to go the way of the Dodo. This isn’t going to be an overnight phenomenon. Radical changes like this take half a decade or more to complete and even at the end there will be a market for legacy systems.


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6 Ways SSDs Are Cheaper Than Hard Drives

With all the hype and counter-hype on the issue of solid-state drives versus hard-disk drives, it’s a good idea to step back and look at the whole pricing picture. This is a confluence of the relative cost per TB of flash die versus HDD assemblies, the impact of SSD performance on server count for a given workload, and the differential in markups by OEM vendors to their end users.

The capacity of flash die has been increasing at an explosive rate over the last year. The “simple” concept of stacking flash cells in the third dimension, coupled with the stacking of these 3D die on top of each other to make a “super-die” has grown capacity by as much as 256 times per flash chip. To put this in perspective, HDD capacity took over 20 years to achieve what SSDs have done in a single year.

I believe SSDs beats HDDs in most use cases today based on total cost of ownership. I’m not just talking power savings, which are typically $10 or $12 per year. SSDs are blindingly fast and that makes jobs run fast, too. The result is you need fewer servers and in many cases these savings offset the additional costs of SSDs.

TCO calculation and the cost comparison between SSD and HDD is complicated by model class and drive markup approaches by vendors. Traditionally, we distinguished enterprise drives with dual-port SAS interfaces from nearline drives with SATA. This distinction has fallen apart in SSDs. Many storage appliances don’t need enterprise dual-port drives, while NVMe is replacing SAS and soon SATA as the SSD interface. For many applications, low-cost SSDs are adequate for the job, which changes buying patterns.

Typical OEM vendor markup ratios are as much as 14X for SSDs, making them even more expensive than raw cost would suggest compared with HDDs that typically see 10X markups or less. COTS systems are starting to drive these markups down, while buying from drive makers directly (if you are a major cloud service provider) or from master distributors (for mere mortals) opens the door to much lower SSD prices.

There are underlying trends in IT that factor into the cost of storage. First, we are rapidly migrating away from the traditional mainstay of storage, the RAID array, to more compact storage appliances that have much more software content, and, with fewer SSD drives, are able to deliver much more data. Second, the new storage appliances use the high bandwidth of SSDs or flash to compress stored data as a background job. HDDs are too slow to do this. The result is much more storage for the same price.

Let’s look more closely at these factors that make SSDs more economical in the long run.

(Image: jules2000/Shutterstock)

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