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SSDs: A gift and a curse

laur.ie

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Re: SSDs: A gift and a curse

#41

Post by Lagged2Death »

On the upside, [the ridiculously expensive HP SSDs] do have fancy detailed stats (like wear levelling) exposed via the controller and ILO, and none have failed yet almost 3 years on (in fact, they’re all showing 99% health). You get what you pay for, luckily.

Call me a huge cynic if you must, but given the other problems observed, I think there's a really simple explanation for perfectly uniform "99% health" after three years of service that doesn't involve "you get what you pay for."

Re: SSDs: A gift and a curse

#42

Post by wtallis »

whyoh wrote: post #39
scott_karana wrote: post #24

Earlier quoted context omitted.

Since when has Intel been hit equally?

For example, the Intel 520 and 530 series have known issues. Besides the lower performance after some amount of writes, they also tend to randomly "disappear" from the system, which is much worse. Google it, it should be easy to find many related topics. I don't know if this only affects the SATA SSDs or not, but it happens a lot. (BTW, the random disappearing also affects some other SSDs from other brands.)

The Intel SSD 520 and 530 use SandForce controllers, so Intel started with a big mess and spent months trying to clean it up before shipping the drives. Clearly they missed a few bugs, and they couldn't work around every mistake and design limitation in the controller's hardware.

Intel's in-house designs have an extremely good track record. I'm only aware of two major bugs.

Re: SSDs: A gift and a curse

#43

Post by noobie »

mrb wrote: post #10

Of course SSD firmware is buggy. You know why? Because any half-decent electrical and computer engineering team can slap a NAND flash controller and some flash chips on a PCB, take the controller's manufacturer's reference firmware implementation, tweak the dozens of knobs provided by the reference implementation (ignore FLUSH commands, change the amount of reserved sectors, disable this, enable that, etc), change th…

Excuse me but most of what you typed went right over my head. Where can one start learning about SSD/HDD firmware and most of what you said?

Re: SSDs: A gift and a curse

#44

Post by nqzero »

justinsb wrote: post #2

I am looking forward to the day when all SSDs ship minimal firmware, and offload all the complex work to (main-CPU) software.

this would be a huge win for database design - FTL is incredibly wasteful in terms of unnecessary block erases for cache

Re: SSDs: A gift and a curse

#45

Post by marssaxman »

Turing_Machine wrote: post #22
rwmj wrote: post #3

Earlier quoted context omitted.

Unfortunately that day isn't going to happen. In fact the opposite is happening -- interesting spinning rust technology like Shingled Magnetic Recording (SMR) drives are getting more complex translation layers.

I wouldn't say that it's never going to happen based on current trends. This kind of thing tends to be quasi-cyclic. At one time, desktop computers had separate FPUs. Over time, those got integrated onto the main CPU, but then the trend switched back, with heavy calculations moving off-CPU to the GPU. The mainframe->desktop->cloud story is similar. I say "quasi"-cyclic because (e.g.) cloud isn't really the same as ma…

I'm eagerly awaiting the part of the cycle where the GPU gets folded back into the processor. I'm really not interested in writing code against mystery-meat architectures with no documented ABI...

Re: SSDs: A gift and a curse

#46

Post by wtallis »

Lagged2Death wrote: post #41

On the upside, [the ridiculously expensive HP SSDs] do have fancy detailed stats (like wear levelling) exposed via the controller and ILO, and none have failed yet almost 3 years on (in fact, they’re all showing 99% health). You get what you pay for, luckily. Call me a huge cynic if you must, but given the other problems observed, I think there's a really simple explanation for perfectly uniform "99% health" after th…

A SSD can be 85% of the way through its lifespan and still be operating with the same performance and reliability expectations it had when it was almost new, so the drive can reasonably be said to still be healthy. It's only when it has to start retiring bad blocks and expending the spare area that the drive is operating in a degraded mode, and it's not until you hit that point that the drive can start making accurate predictions about how much more use it can take until it dies.

Re: SSDs: A gift and a curse

#47

Post by [deleted] »

jacquesm wrote: post #12
mrb wrote: post #10

Of course SSD firmware is buggy. You know why? Because any half-decent electrical and computer engineering team can slap a NAND flash controller and some flash chips on a PCB, take the controller's manufacturer's reference firmware implementation, tweak the dozens of knobs provided by the reference implementation (ignore FLUSH commands, change the amount of reserved sectors, disable this, enable that, etc), change th…

And, contrary to a fly-by-night SSD manufacturer that's here today and gone tomorrow they have a reputation to protect and they suffer big time if a batch of faulty drives hits the market. See 'deathstar' and other re-runs of that concept. So they work very hard to make sure that doesn't happen to them.

[deleted]

Re: SSDs: A gift and a curse

#48

Post by pgeorgi »

wtallis wrote: post #40
bduerst wrote: post #36

Earlier quoted context omitted.

Doesn't that require partitioning the disk? That doesn't seem like an OOB solution.

It's not the requirement to partition the drive that kills the idea. Setting aside the first small chunk of the drive for the firmware to read is how it's always been done. The problem is that this would require the partitioning to be done below the wear leveling layer, which reduces the effectiveness of the wear leveling slightly and means you can only change your bootloader settings a thousand times before the driv…

sadly with NAND even reads contribute to wear.

Re: SSDs: A gift and a curse

#49

Post by MaulingMonkey »

Lagged2Death wrote: post #41

On the upside, [the ridiculously expensive HP SSDs] do have fancy detailed stats (like wear levelling) exposed via the controller and ILO, and none have failed yet almost 3 years on (in fact, they’re all showing 99% health). You get what you pay for, luckily. Call me a huge cynic if you must, but given the other problems observed, I think there's a really simple explanation for perfectly uniform "99% health" after th…

"There's already been silent failures"?

Re: SSDs: A gift and a curse

#50

Post by zanny »

mrb wrote: post #10

Of course SSD firmware is buggy. You know why? Because any half-decent electrical and computer engineering team can slap a NAND flash controller and some flash chips on a PCB, take the controller's manufacturer's reference firmware implementation, tweak the dozens of knobs provided by the reference implementation (ignore FLUSH commands, change the amount of reserved sectors, disable this, enable that, etc), change th…

Sounds almost like having free software SSD firmware would be a nice thing. I just love how I have microcontrollers on all my persistent storage devices now that operate as a black box made by incompetent or possibly malicious developers.
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