SSDs of Infinite Resource and Sagacity

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Returning to NVME.

Several aspects of this supremely efficient protocol made it worthy successor to AHCI, which, after a decade of faithful service, stood poised to reveal its age. The most momentous enhancement was without question, its ability to process command queues of fantastically greater depth in parallel. Whereas ACHI was limited to a single queue of 32 commands, NVMe was capable of addressing over 65000 queues, each over 65000 commands in length.

For a fantastically crude but entertaining analogy, consider a customer at your local supermarket with 32 items in his trolley and a loan member of staff to swipe his groceries across the machine that goes *BEEP*.

Directly behind is another figure, a disgruntled lady in a desperate hurry, two baskets stuffed with an amalgam of condiments, vegetables and ready meals, also totalling 32 and after her, a second gentlemen, trying his dandiest to be patient but in truth, most aggrieved of all due do his irrational desire to ingest 32 packets of Ginger nuts. Enter the store manager, Mr Norman Virtue Morris Evans (Nvme for short).

“Don’t worry”.  He assures.  “Today we a setting in motion an inspiring new initiative.  No doubt you’ll be familiar with our rival’s hollow promises to open a new checkout whenever a customer is forced to wait in line.  Well, when we make such pledges, we provide, and that’s putting it mildly.

Recently, one of our most illustrious benefactors, a Mr. Von Intel, made an extremely generous donation, on the strict stipulation that every penny, pound, dollar and dime was invested to ensure a spiritual shopping experience for our priceless clientèle. It is thus with pride that I announce, in approximately one hour, every aisle in this supermarket will be adorned with the richest repertoire of produce imaginable.  Choices so abundant you shall shed tears of dumbfounded delight.  A tea for every hour of the day.

A coffee for every sentence of an agitated email. Cupcakes where before there were no cups.  Non-alcoholic potatoes, genetically reformed bananas. Sugar free cereal, cereal free cornflakes, Paleo friendly porridge, free range mineral water, big fat cheese, thin carbohydrate butter, fractionally lower than medium protein milk.  Gluten-absent, farm reared chocolate and openly organic baguettes.”

As you’ll have probably guessed, this futile variety of foodstuffs and the shelves it populates, are metaphors for hard drive’s data and memory chips.

“With such an abundance of choice,” continues Norman, bristling with enthusiasm.  “One extra checkout would scarcely suffice, which is why, as of 11 o clock this morning, we’ll be opening precisely 65535.”

As you’ll have gathered by now, these checkouts allude to the number of simultaneous command queues an NVMe drive can attend to.

“And how about a special bonus”  Norman went on, addressing our three faithful foragers.  “Why don’t you go grab one of our  swanky new trolleys over by the entrance?  You may find them rather awkward to begin with, their proportions a trifle large for comfort, but trust me, this whole project would have worthless if we’d stuck with the old design.  Most importantly, there’s not a wobbly wheel amongst them.  Now here’s a challenge I know you’ll love.  Each of you decant your 32 purchases to a trolley, then abandon civility and try to cram in another 65504.

You with biscuits, go to the confectionery aisle and only pick items from there, pile em as high as you can.  And you two, mix it up, stash stuff from everywhere else, as wider selection with as many different prices as possible, from £5 puddings to 40 pence peaches.”

As you’ll have astutely surmised in this increasingly contrived parable, the items removed from shelves are chunks of data – £5 = 512k and 40p = 4k – while the shoppers with their trolleys, symbolize software scurrying around the drive and accumulating read commands.

Customer’s one and two, with their broad assortment of sustenance, equate to random read requests from the SSDs memory, whilst our voracious biscuit addict, represents sequential reads.

“Once you’ve finished,” Norman instructs.  “Roll those baskets back to the checkouts, relax, and allow our solicitous packer in chief to scan and bag your rations ready for the world outside.  He looks a little odd, he was made redundant as a circus juggler because the tumblers and tiger tamers felt upstaged by his act, but don’t let his size or his 65536 arms intimidate you.

He completed our training program with flying colours, his coordination is second to none, he can multi task as seamlessly as any woman of woman born.  If the machines fail, he knows every bar-code and price by heart, he’s remarkably convivial and best of all, since each of his hands can serve a separate checkout, he’s over 65000 times cheaper to employ.  We’re don’t actively seek to undercut the minimum wage but when someone applies for a job out of pure passion and appears uncannily well-qualified, why deprive them of the pleasure of fulfilling their purpose?

Finally, allow me to introduce another inspiring incentive devised to prevent the anti-social sterility of  on-line foraging from perniciously eroding our ability to interact. Each of you privileged customers has been appointed a personal stock checker with a trolley that matches the dimensions of yours, along with their own inverted checkout.  Let’s call it a check-in. As you choose supplies, your entire harvest will be studiously logged with replenishments conducted as required and tactful dietary suggestions made in anticipation of your next gracious visit.  Please don’t let us down.”

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