|IDC & TrendForce data
via Aaron Rakers
Aaron Rakers, the Wells Fargo analyst, thinks enterprise storage buyers will start to prefer SSDs when prices fall to five times or less that of hard disk drives. They are cheaper to operate than disk drives, needing less power and cooling, and are much faster to access.Below the fold, some skepticism.
So when will the wholesale switch from nearline HDD to SSDs begin? We don’t have a clear picture yet but a chart of $/TB costs for enterprise SSDs and nearline disk drives shows how much closer the two storage mediums have come in the past 18 months.The chart is interesting but I think Rakers estimate of 5x as the tipping point is too optimistic, for several reasons:
It is unwise to extrapolate too much but it is clear the general trend direction is that Enterprise SSD cost per terabyte is falling faster than nearline disk drive cost/TB. Our chart below shows the price premium for enterprise SSDs has dropped from 18x in the fourth 2017 quarter to 9x in the second 2019 quarter.
- The purchase cost of an HDD is much more than 20% of the power and cooling costs over its service life.
- So the benefit of the extra speed would have to be large. But nearline drives only see accesses that the SSDs above them in the storage hierarchy don't handle. So speed isn't as important as low $/TB. Speed in nearline is nice, but it isn't what the nearline tier is for.
- As SSDs get cheaper, the size of the tier above will grow slowly but steadily relative to the nearline tier. The upper tier will service more of the traffic, which will reduce the benefit of SSD's speed in the nearline tier. At 5x their cost won't justify wholesale replacement of the nearline tier.
- The recent drop in SSD price reflects the transition to 3D flash. The transition to 4D flash is far from imminent, so this is a one-time effect.
- Industry projections should always be taken with many grains of salt, as my earlier posts about the good Dr. Pangloss indicate.
Western Digital shares my skepticism, as Chris Mellor now reports in Holy MAMR: Western Digital's 18TB and 20TB microwave disk drives out soon:
Western Digital said demand for high-capacity data centre disk drives will keep up over the next few years as it told the world it would begin shipping samples of its new MAMR 18 and 20TB drives over the next four months.
|Seagate's 2009 roadmap
WD will sample the HC650 and HC550 drives to select customers by the end of the year, with qualification and volume shipments beginning in the first half of 2020. In other words, volume ships of these drives could be up to nine months away.