Technical Information/Support RequestsSSD's OBSOLETE

Just as the title says

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sidewinder9x
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Sun Mar 01, 2015 8:58 am

Interesting read from ZNET:


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Why SSDs are obsolete

Summary:Solid State Drives - SSDs - are a product of convenience, not good architecture. Storage systems need to be re-architected to achieve the highest performance of NAND flash and, soon, byte-addressable non-volatile memory. Here's an example.

By Robin Harris for Storage Bits | February 26, 2015 -- 12:14 GMT (04:14 PST)
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SSDs were built because there are billions of SATA and SAS disk ports available. Filling some of those ports with SSDs promised to be quite profitable - a promise fulfilled in the last 5 years.

But now that non-volatile memory technology - flash today, plus RRAM tomorrow - has been widely accepted, it is time to build systems that use flash directly instead of through our antique storage stacks. The various efforts to decrease latency - SATA 3, NVMe, and others - still add layers of software between our applications and our data, creating complexity and wasting CPU cycles. A recent PhD thesis got me to thinking about this.
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Indirection

A famous computer science aphorism states "All problems in computer science can be solved by another level of indirection, except for the problem of too many layers of indirection." When that happens some of those layers have to go.

We're at that point with SSDs. SSDs rely on a Flash Translation Layer (FTL) that makes flash - with its slow writes and limited endurance - look like a disk drive. The FTL is a layer of indirection.
FTL obsolescence

File systems already provide a layer of indirection by treating storage devices as contiguous logical address spaces. They manage the logical addresses by maintaining detailed metadata including bitmaps that track the device's block allocation.

However, the FTL also maintains a contiguous logical address space behind which activities such as wear-leveling and garbage collection are hidden. The obvious question is: why maintain two logical address spaces? Why not have the file system directly manage the flash?

If we got rid of the FTL, SSDs would be faster, lower cost, and more reliable. What's not to like?
The Storage Bits take

SSDs are obsolete in an architectural, not functional, sense. They offer many advantages over disk drives, which will also continue to sell in the hundreds of millions for years to come, but the motivating idea behind SSDs - fill those SATA ports! - is less and less relevant to today's systems.

We need to incorporate flash and, soon, byte-addressable NVM memory, as they are, rather than making them seem like disks. This is no small effort, but with the slowing of processor performance increases, systems need to find performance elsewhere. The storage stack is ripe for disruptive improvement.

Comments welcome, of course. While this post was inspired by Yiying Zhang's excellent PhD thesis, I'm responsible for any over-simplifications and errors.

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sidewinder9x
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Sun Mar 01, 2015 9:57 am

Cybex and I were discussing many things this Sunday morning and we go on the subject of computer storage (see SSD story) of the human brain; specifically "if you were a person who had the ability to remember every thing that occurred in your life and those around you and you live to be 100 years old how much storage space would that take up if you were to transcribe it all every day of your life"?

Here is the general consensus of the human brain storage:

... neurons combine so that each one helps with many memories at a time, exponentially increasing the brain’s memory storage capacity to something closer to around 2.5 petabytes [1 petabyte ≈ 1,000 terabytes]. For comparison, if your brain worked like a digital video recorder in a television, 2.5 petabytes would be enough to hold three million hours of TV shows. You would have to leave the TV running continuously for more than 300 years to use up all that storage.

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KungfuBeer
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Sun Mar 01, 2015 11:39 am

I merged the topics, both interesting, and very close topics.
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MissileChicago
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Mon Mar 02, 2015 6:17 am

The evolution of technology is real and ever present.
.

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Druzin
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Tue Mar 03, 2015 12:05 pm

The report lost me when it started talking about architecture and FTL (I read enough to determine they didn't mean faster than light :-( ). Is the next thing that makes SSD obsolete coming soon or still an experimental theory like organic/crystal computers?

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sidewinder9x
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Tue Mar 03, 2015 4:15 pm

One word: FLASH...

Read about it online..

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Druzin
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Thu Mar 05, 2015 10:09 am

[youtube]Yj0l7iGKh8g[/youtube]

:cry:

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sidewinder9x
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Thu Mar 05, 2015 2:55 pm

Please, no cheezy Bollywood re-make movies!

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