Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Everything I know about SSDs (2019)

kcall.co.uk

Post reply on HN
Print view View original

41–50 of 53 posts

Re: Everything I know about SSDs (2019)

#41

Post by epcoa »

jmbwell wrote: post #17
ThrowawayR2 wrote: post #12

Earlier quoted context omitted.

EPROMs were erased by many minutes of exposure to UV light, not a flashbulb, in a device called a UV eraser. I've never heard anyone refer to any operation on an EPROM as "flashing".

Yep, "UV eraser" confirmed by an elmer I know. A unit with a drawer and a timer knob, he says you'd typically set for 30 minutes. He says he does recall people calling it "flashing," but not until much later, by which time it would have been actual "flash" memory. As for my own memory, I'm going to file this under Mandela Effect, cross-referenced under Things People Probably Told Me That I've Believed Since Before Th…

Still own and use a little 9V plastic “portable” UV EPROM eraser that I’ve had for 30 years. Never heard the term “flashing” in this use even when I used them commercially. It really makes no sense what it has to do with flashing, it’s a steady gas discharge lamp for 10 to 20 minutes.

The process of programming EPROM was colloquially called “burning” whereas for Flash the programming is called “flashing”, despite the characteristic that the name originally refers to is fast erase speed.

Re: Everything I know about SSDs (2019)

#42

Post by avidiax »

hex4def6 wrote: post #36
sgerenser wrote: post #8

Earlier quoted context omitted.

I never heard of using a literal flash to reprogram EPROMs, but this wikipedia entry[1] makes your story for the origin of the term “Flashing” seem likely EPROMs are easily recognizable by the transparent fused quartz (or on later models resin) window on the top of the package, through which the silicon chip is visible, and which permits exposure to ultraviolet light during erasing. [1] https://en.m.wikipedia.org/wik…

Heard from a greybeard that they had a demo night in university (this was probably early 80s), and one of the demos was was some sort of path-finding rover robot. Of course, it ended up being one of those projects that had show stopping bugs up until a few hours before showtime. During demo night, it was a big hit, until a stray camera flash got (un)lucky and wiped the microcontroller's EEPROM... Feels a little apocr…

This still happens today. Some chip packaging doesn't provide enough protection from UV.

https://forums.raspberrypi.com/viewtopic.php?f=28&t=99042

Re: Everything I know about SSDs (2019)

#43

Post by asciimov »

hex4def6 wrote: post #36
sgerenser wrote: post #8

Earlier quoted context omitted.

I never heard of using a literal flash to reprogram EPROMs, but this wikipedia entry[1] makes your story for the origin of the term “Flashing” seem likely EPROMs are easily recognizable by the transparent fused quartz (or on later models resin) window on the top of the package, through which the silicon chip is visible, and which permits exposure to ultraviolet light during erasing. [1] https://en.m.wikipedia.org/wik…

Heard from a greybeard that they had a demo night in university (this was probably early 80s), and one of the demos was was some sort of path-finding rover robot. Of course, it ended up being one of those projects that had show stopping bugs up until a few hours before showtime. During demo night, it was a big hit, until a stray camera flash got (un)lucky and wiped the microcontroller's EEPROM... Feels a little apocr…

You would have put some tape over the window to keep that from happening.

Also erasing takes like 15+ mins, it wasn’t quick.

Re: Everything I know about SSDs (2019)

#44

Post by dboreham »

jmbwell wrote: post #5

I always thought 'flash' was a holdover from early reprogrammable ROM technology, non-volatile memory that you could erase by literally flashing a literal flashbulb over a little window on the chip. I would've sworn in a court of law that I recall this being called "flashable" memory, that erasing it was called "flashing" it, and reprogramming it in general was called "reflashing" in a sort of synecdoche. And I'd hav…

> holdover from early reprogrammable ROM technology, non-volatile memory that you could erase by literally flashing a literal flashbulb

No. I can see how that might appear plausible but they're unrelated. Flash was a marketing term invented to differentiate a new EEPROM technology that allowed much higher density, and featured sector erase, from previous EEPROM tech. This was done because engineers saw EEPROM as esoteric expensive tech that had no place in low cost products. The Flash vendors wanted to position the new chips as replacing UVPROM, which was relatively cheap by comparison. So they came up with a name that was a) not EEPROM and b) conveyed that the devices were quickly reprogrammed vs UVPROMs (which had to be baked in an eraser then took some minutes to program in a special piece of equipment).

Flash's big advantage was that it could be programmed on-board, allowing soldered down PROMs, surface mount packages.

Source: I was a hardware design engineer when Flash was introduced and heard the marketing pitch first hand.

Using Flash chips for rewritable bulk persistent storage came much later. The first generation devices didn't have the necessary density.

Re: Everything I know about SSDs (2019)

#46

Post by eimrine »

Eisenstein wrote: post #39
userbinator wrote: post #31

Earlier quoted context omitted.

Note that retention increases exponentially with decreasing temperature, so literally "cold storage" might actually be OK for SSDs. The retention also goes down with erase cycles, and is usually specified after the rated number of cycles have been reached; I expect those same SSDs to hold their data much longer than 3 months if they're still nearly new. I still have USB drives over a decade old, but their contents ar…

Those are drives that weren't plugged in for a decade? How do you know the contents are intact?

Probably by plugging it in and eyeballing all the contents. I have a similar experience with 1GB ancient USB drive.

Re: Everything I know about SSDs (2019)

#47

Post by numpad0 »

jmbwell wrote: post #5

I always thought 'flash' was a holdover from early reprogrammable ROM technology, non-volatile memory that you could erase by literally flashing a literal flashbulb over a little window on the chip. I would've sworn in a court of law that I recall this being called "flashable" memory, that erasing it was called "flashing" it, and reprogramming it in general was called "reflashing" in a sort of synecdoche. And I'd hav…

Actually no, it’s Toshiba trademark for then-new type of EEPROMs that could be erased quickly in blocks rather than having to be set and unset bit by bit.

Intel had italic stylized “FLASH” logo proudly printed on chips. I’ve come across it once.

Re: Everything I know about SSDs (2019)

#48

Post by themoonisachees »

magnetic wrote: post #30
Vecr wrote: post #27

Earlier quoted context omitted.

Did you stagger the power-on times? Otherwise you could get tightly correlated failures.

They are about 25 hours apart, which isn't very large I'll admit. Thankfully, the serial numbers aren't too close to each other, so I'm hoping they aren't part of the same batch.

In my experience with enterprise SSDs (which yeah aren't the same but that's what I have to offer), SSDs with sequential serial numbers and identical on-times, in the same RAID array, can have wildly different actual endurance. Some storage servers I used to admin had SSDs lasting longer than 2 neighbor replacements from the same original box, and this happened at least twice.

I stopped being worried about on-times after that for SSDs. HDDs are still quite correlated (on the order of months) but if you're building the server you have to put the disks in it at some point.

Re: Everything I know about SSDs (2019)

#49

Post by themoonisachees »

somat wrote: post #38
password4321 wrote: post #7

I've heard SSDs are more likely to "fail fast". Can anyone recommended utilities that monitor and warn before SSD failures?

One surprising feature of "enterprise" class drives is that they often have a faster fail than their consumer class counterparts. the idea being an enterprise class drive will be found in a drive array, and the array will be much happier with a hard fast final failure than a drive that tries to limp along. While the consumer with their single drive is a lot happier when their failing drive gives them every chance to…

Often times you'll find that consumer drives that are limping around do fail smart checks and would absolutely flash a red light and send out a monitoring alert were they in an enterprise enclosure. While there is probably truth to what you're saying, I think the enterprise is also just way more proactive at testing drives and calling them dead the instant the smart checks fail, where consumers don't typically use crystaldiskinfo.

Re: Everything I know about SSDs (2019)

#50

Post by Eisenstein »

eimrine wrote: post #46
Eisenstein wrote: post #39

Earlier quoted context omitted.

Those are drives that weren't plugged in for a decade? How do you know the contents are intact?

Probably by plugging it in and eyeballing all the contents. I have a similar experience with 1GB ancient USB drive.

Did you literally never plug the drive in for over a decade or so, not once? Then you checked the contents for corruption and it was clean?
Post reply on HN