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Why I'm usually unnerved when modern SSDs die on us

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Re: Why I'm usually unnerved when modern SSDs die on us

#131

Post by rabidrat »

tzs wrote: post #75
lisper wrote: post #63

This is not a technological problem, it's a cultural one. These problems are easily fixed ("easily" by the standards of technical problems that regularly get fixed in other regimes). The reason they don't get fixed is that the customer reaction to failures like this is to rant at the mysterious storage gods that are making their lives miserable. Needless to say, there are no mysterious storage gods. These are artifac…

> Needless to say, there are no mysterious storage gods What about Consus, the god who protected grain storage in the ancient Roman religion? [1]. Or Eopsin, the Korean goddess of storage? [2] [1] https://en.wikipedia.org/wiki/Consus [2] https://en.wikipedia.org/wiki/Eopsin

Those gods are not so mysterious, are they.

Re: Why I'm usually unnerved when modern SSDs die on us

#132

Post by blattimwind »

Mister_Snuggles wrote: post #49
rsync wrote: post #41

Earlier quoted context omitted.

"It feels like the author's main complaint is the frustration of not understanding SSD hardware as well." What is so frustrating about SSDs is how very poorly they compare to previous incarnations of solid state storage. Using Disk-On-Chip and/or IDE-pin-compatible CF cards, I had many, many devices in the field that lasted, mounted read-only, for decades An entire sect of the computing industry came to rely on these…

I've heard very similar advice for non-SSD mirrors too. Use different manufacturers or, at the very least, use different batches of disks from the same manufacturer.

Most importantly, never assemble an array from drives that took the same shipping path i.e. came out of the same parcel.

Re: Why I'm usually unnerved when modern SSDs die on us

#133

Post by blattimwind »

pjc50 wrote: post #27
Wowfunhappy wrote: post #18

Earlier quoted context omitted.

Is there a good reason why we use separate SSD controllers instead of letting the primary cpu handle it? The obvious reason is backwards compatibility, but as more of computing moves to SSDs, is this still relevant? ZFS has shown that removing layers of abstraction with regard to storage can be beneficial.

That adds a round of latency, and makes it pretty much impossible to boot off the drive. The blocks aren't in the same order in the Flash as they are presented by its interface, and one of the main jobs of the controller is to re-order them. It would be an interesting product to have, a raw block API to a Flash device with all the temporary state stored on the host - but a hard one to sell, as it's not differentiated…

There are host-managed SMR drives, which share a number of characteristics with flash storage.

Re: Why I'm usually unnerved when modern SSDs die on us

#134

Post by blattimwind »

blincoln wrote: post #47
Waterluvian wrote: post #5

"When a HD died early, you could also imagine undetected manufacturing flaws that finally gave way. With SSDs, at least in theory that shouldn't happen" Why shouldn't it? Isn't it just hardware too? "With spinning HDs, drives might die abruptly but you could at least construct narratives about what could have happened to do that" Why can't you do the same with SSDs? It feels like the author's main complaint is the fr…

Why shouldn't it? Isn't it just hardware too? In a mechanical hard drive, there are moving parts which can wear out due to friction, etc. SSDs are solid-state, so it seems like at least theoretically, it should be possible to build one that keeps working for decades. e.g. I have solid-state hardware from the 70s and 80s which still functions. I've always been a little mystified as to why SSDs' data areas wear out for…

> I've seen lots of writeups of how wear-leveling works, etc., but never a good physical explanation of what is actually wearing out over time.

SSDs are flash are basically EEPROMs. In an EEPROM one bit is stored in a dual-gate MOSFET. One Gate is a normal gate, the other is floating, i.e. it just is a small conductive island. The information is stored by (quite literally) shooting electrons through the insulation of the floating gate into it. They're then trapped on the gate; if you turn the second gate on, the transistor conducts iff the floating gate is also turned on. This shooting action happens to damage the insulation, which at some point is degraded enough that it can't keep the electrons trapped on the floating gate. Hence the electrons leave, together with your information.

> For devices manufactured after about 2000 there's tin whiskers,[3] which began to be a problem because of RoHS requirements.

The solder joints themselves usually don't form whiskers, which mostly grow on pure tin-plated surfaces, e.g. the pins of components (which previously used lead). Using lead-free solder is mostly co-incident with whisker risk, not the cause of the majority of problems.

Re: Why I'm usually unnerved when modern SSDs die on us

#136

Post by sigstoat »

listic wrote: post #126
sigstoat wrote: post #77

Earlier quoted context omitted.

just based on having seen data recovered from other flash devices, and the advertising copy of these devices: hot-air rework to lift all the flash chips off and get them hooked up to something (probably custom) that can read them. if the controller was encrypting everything that went to flash, you also get to try and find the key in the controller's memory.

why something custom? shouldn't you just solder the chips into an identical donor ssd?

a new controller is probably worthless to you, even if the old one wasn't storing the data encrypted. you don't have the map between real sectors and locations in flash.

your data is probably jumbled up one way or the other, but at least a custom board will let you read all of the underlying flash, instead of just the portions of it that a new controller would believe are in use. (keep in mind that the SSDs will have more physical blocks than they advertise logically.)

Re: Why I'm usually unnerved when modern SSDs die on us

#137

Post by dgzl »

agumonkey wrote: post #124
Matthias247 wrote: post #113

Earlier quoted context omitted.

> Another problem is that the job while rewarding is not very lucrative. The chance of a multi million dollar payoff for an employee is low. I have a higher chance working on a web connected gadget to become a millionaire. So that means it is really hard to recruit those who are top notch programmers who known how to figure out the algorithms, write the code, debug the hardware. Most new grads these days are interest…

I don't know how the system could / should interface with stupid trends sucking resources (high complexity projects, smart individuals, long term).

The business would have to offer employees something lucrative they otherwise wouldn't earn. I'm not sure what that would be however.

Re: Why I'm usually unnerved when modern SSDs die on us

#138

Post by [deleted] »

pkaye wrote: post #91

I worked on SSD firmware for quite a long time and here is my perspective. Early flash used to fairly reliable with almost minimal error correction. However with increasing density, smaller processes and multi level cells, it has gone progressively less reliable and slower. Here are some of the things that we need to worry about: https://www.flashmemorysummit.com/English/Collaterals/Procee... To compensate for all th…

[deleted]

Re: Why I'm usually unnerved when modern SSDs die on us

#139

Post by LeftTurnSignal »

shittyadmin wrote: post #2

I've experienced a few seriously strange issues with modern SSDs, even some of the better ones. I had a 512GB Samsung drive that became very slow randomly at doing IO operations, the whole machine would die for 10-30 seconds at a time once or twice a day while any process that tried to use the disk became blocked on IO. Then it'd come right back like everything was perfectly fine. Issues like this definitely worry me…

I've recently noticed similar issues with my older Crucial SSD in my 2012 mbp.

In the past 3 months, there's been maybe 5 times where I started my laptop and it took 5+ minutes to finish booting. Normally, it's 15 seconds. Once I'm logged in, doing anything takes forever, but it does eventually load. A power off, and back on got it "working" again but who knows for how long.

I've had this drive for 4-5 years now, so I'm impressed it's lasted this long.

Re: Why I'm usually unnerved when modern SSDs die on us

#140

Post by apetresc »

loeg wrote: post #104
godzillabrennus wrote: post #99

Earlier quoted context omitted.

As someone that identified a bug in a Drobo firmware once and was offered a job on the spot I think the problem with attracting talent is two fold. The first problem is really two parts, not only is it rare to find people who have passion for storage related technologies but very few will gain exposure to these technologies to develop that passion. Kids don't routinely grow up with a SAN in the house. They do tend to…

I'm mostly curious because I work in a storage-adjacent field (NAS) for a BigCorp and the pay is pretty good, if not quite FAANG level. It's not a startup by any means, but I will easily become a multi-millionaire in a handful of years. I was curious about the other side of the fence.

Huh? If you're going to "easily become a multi-millionaire in a handful of years", then your pay is more than pretty good, and certainly not worse than FAANG level.
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