Tuesday, November 01, 2011

Flash Memory vs 15,000 RPM drives

Some I.T. technologies  have a limited life or "use window". For example:
In 2001, the largest Compact Flash (CF) card for Digital cameras wasn't flash memory, but a hard disk, the 1Gb IBM "microdrive" ($500 claimed price). After Hitachi acquired the business, they produced 4Gb and 6Gb drives,  apparently for sale as late as 2006, with the 4Gb variant used in the now discontinued Apple iPod mini.
Around 2006, the 1" microdrive hard disks were out-competed by flash memory and became yet another defunct technology.

Flash memory storage, either SSD or PCI 'drives', for servers now cost A$2-3/Gb for SATA SSD and $3-4/Gb for PCIe cards [A$3/Gb for Intel mini-PCIe cards].

Currently, Seagate 15k 'Cheetah' drives sell for around $2/Gb, but their 2msec (0.5k IO/sec) performance is no match for the 5KIO/sec of low-end SSD's or the 100-250KIO/sec of PCI flash.

10,000 RPM 'Enterprise' drives cost less, around $1.50/Gb, whilst 1Tb 7200 RPM (Enterprise) drives come in at $0.25/Gb.

The only usual criteria 15,000 RPM drives beat other media on is single-drive transfer rate*.
Which in an 'Enterprise' RAID environment is not an advantage unless a) you're not paying full price or b) you have very special requirements or constraints, such as limited space.

I'm wondering if 2010 was the year that 15,000 RPM Enterprise drives joined microdrives in the backlot of obsolete technologies - replaced in part by the same thing, Flash Memory.

Part of the problem stems from the triple whammy for any specialist technology/device:
  • Overheads are maximised: By definition 'extreme' technologies are beyond "cutting-edge", more "bleeding-edge", meaning research costs are very high.
  • Per Unit fixed costs are maximised: Sales volumes of specialist or extreme devices are necessarily low, requiring those high research costs to be amortised over just a few sales.
    If the technology ever becomes mainstream, it is no longer 'specialist' and research costs are amortised over very large numbers of parts.
  • Highest Margin per Unit: If you want your vendor to stay in business, they have to make suitable profits, both to encourage 'capital' to remain invested in the business and have enough surplus available to fund the next, more expensive, round of research. Profitable businesses can be Low-Volume/High Margin or High-Volume/Low Margin (or Mid/Mid).
Specialised or 'extreme performance' products aren't proportionately more expensive, they are necessarily radically more expensive, compounding the problem. When simple alternatives are available to use commodity/mainstream devices (defined as 'least cost per-perf. unit' or highest volume used), then they are adopted, all other things being equal.

* There are many characteristics of magnetic media that are desirable or necessary for some situations, such as "infinite write cycles". These may be discussed in detail elsewhere.

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