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#16
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SATA Drives
On 1/4/19 5:03 PM, Tim wrote:
nospam wrote in news:040120191635551909% lid: In article , wrote: When I sell an ssd, it has to work and keep working as when SSD's go bad, they brick. false. I see it all the time. The flash cells are not the only thing that fails. The interface electronics also fails too. And that DOES NOT show up on lifespan tests. But pardon me. You know all and see all. I stand corrected. You KNOW IT ALL! No wonder I kill filed your your stupid ass. Idiot. most ssds will fail to read-only, normally long after smart warnings indicating that they're approaching end of life, and that's assuming something else doesn't fail first. ssds will normally outlast the devices in which they are installed. not that it matters, since if one does fail, simply replace and restore from backup. no big deal. I settled on Samsungs as they are the best reliability I could find. Wonderful tech support too. samsung is *among* the best. crucial is also top quality. and an ssd does not need tech support. connect it and it works. done. there may be differences in how they handle warranty service, but that's something else entirely. My first SSD was a Kingston. It died two years into a three year warranty, right after Kingston announced that they were dropping support for it. Just bite the bullet and get a Samsung. Remember to install Samsung Magician to check your lifespan. |
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#17
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SATA Drives
On 1/4/19 5:00 PM, Tim wrote:
T wrote in : On 1/4/19 1:31 PM, T wrote: On 1/4/19 1:27 PM, Tim wrote: nospam wrote in news:040120191558488272% lid: In article , Big Al wrote: Also, Samsung drives are the only high reliability drive I have come across. Stay away from Intel. crucial and samsung are both very good choices. intel is *very* reliable, just not consumer priced (mostly). Thoughts on Inland or Kingston M2.2280's ?? Local brick and mortar store has them $50 US for 250GB My current motherboard has no provision for an M2 drive. I assume I wo uld have to add a PCIe board to home the drive on. At that point is the performance worth the expense? I have not found an add on card I really like for this, so I can't say The not bootable thing annoys the s*** out of me. Does that mean if I want to use an M2 drive for my system drive I would have to have bootable media on a USB or DVD set up to load Windows from the M2? Hi Tim, Okay, M2 is just describes a form factor and a slot on your motherboard. M2 form factor drives can be a SATA drives or NVMe drives. You have to look at your motherboard's spec's to figure out what it will accept. And any add on card's specs too. M2 SATA drives and just a lot smaller than standard SATA drives. They perform exactly the same. NVMe drives are the fast ones. Add on cards have a hard time becoming bootable. Most M2 add on cards I have seen only support M2 SATA drives and are not bootable. So any drive on the add on card would be a second non-bootable drive for extra storage. Disclaimer: this may have changed as I haven't checked recently. Update: this one says it support NVMe drives: https://www.startech.com/Cards-Adapt...d~PEXM2SAT32N1 And their chat line says it is bootable, if your motherboard's bios supports NVMe drive and booting from NVMe drives. If your motherboard does not have its own NVMe M2 slot, I hight doubt it will boot from this adapter. To be certain, check with your motherboard's tech support. -T |
#18
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In article , wrote:
When I sell an ssd, it has to work and keep working as when SSD's go bad, they brick. false. I see it all the time. then you're buying ****ty ssds. overall, ssds are *extremely* reliable, much more so than mechanical hard drives, and rarely brick. however, quality does vary. some aren't as good as others and there are always duds, as there are with any product. The flash cells are not the only thing that fails. The interface electronics also fails too. very rarely. many older ssds did have firmware bugs, but those are mostly a thing of the past and usually didn't cause an entire failure. early hard drives had issues too. And that DOES NOT show up on lifespan tests. nobody said it did. But pardon me. You know all and see all. I stand corrected. You KNOW IT ALL! No wonder I kill filed your your stupid ass. Idiot. nothing more than ad hominem attacks and cowardice. you make a lot of claims but never back them up. Just bite the bullet and get a Samsung. actually, samsung isn't the most reliable, although it is quite good: https://techreport.com/r.x/ssd-endurance-theend/earlyfailures.gif however, noname stuff is best avoided. nothing is perfect and there are both good and bad stories on *every* make. Remember to install Samsung Magician to check your lifespan. there is no need for that or any other lifespan utility since it's exposed in smart and the ssd will likely outlast the device it's in anyway, longer than any mechanical hard drive would have. but in the unlikely event it does fail, replace it, restore from backup. no big deal. certainly not worth obsessing over. |
#19
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On 1/4/2019 8:50 PM, nospam wrote:
In article , wrote: When I sell an ssd, it has to work and keep working as when SSD's go bad, they brick. false. I see it all the time. then you're buying ****ty ssds. overall, ssds are *extremely* reliable, much more so than mechanical hard drives, and rarely brick. however, quality does vary. some aren't as good as others and there are always duds, as there are with any product. The flash cells are not the only thing that fails. The interface electronics also fails too. very rarely. many older ssds did have firmware bugs, but those are mostly a thing of the past and usually didn't cause an entire failure. early hard drives had issues too. And that DOES NOT show up on lifespan tests. nobody said it did. But pardon me. You know all and see all. I stand corrected. You KNOW IT ALL! No wonder I kill filed your your stupid ass. Idiot. nothing more than ad hominem attacks and cowardice. you make a lot of claims but never back them up. Just bite the bullet and get a Samsung. actually, samsung isn't the most reliable, although it is quite good: https://techreport.com/r.x/ssd-endurance-theend/earlyfailures.gif however, noname stuff is best avoided. nothing is perfect and there are both good and bad stories on *every* make. Remember to install Samsung Magician to check your lifespan. Can you explain lifespan in laymen's terms? I don't remember the exact numbers, but terms like MTBF are often misconstrued. IIRC MTBF is the time by which a significant percentage of devices will fail. In aggregate, that number is useful for estimating warranty failures. But for the individual, it's meaningless. Your device is either dead or it is not. MTBF doesn't mean that YOUR device will last that long, or even close to that long. All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? How does TBW inform the single user? And what does it measure anyway? SMART reports system writes. Does that include write amplification? If you don't abuse it mechanically or thermally, a HDD has few sources of wearout. The SSD has a GUARANTEED source of wearout. You are mechanically abusing the cells at the micro level and taking epic measures to spread that wearout and recover from inevitable cell failure with error correction. It's a leaky bucket that you keep patching with duct tape. When you run out of duct tape, you're done...maybe... there is no need for that or any other lifespan utility since it's exposed in smart and the ssd will likely outlast the device it's in anyway, longer than any mechanical hard drive would have. If you buy new computers and update regularly, I believe that's the case. For those of us who buy the computers you discarded, thank you very much, and use them for another decade, not so much. but in the unlikely event it does fail, replace it, restore from backup. no big deal. certainly not worth obsessing over. That's easy to say, but how many actually do that. I frequently image 22GB of C: drive. But there's a terabyte of stuff on there that isn't backed up regularly. I've got nowhere to put it. And I've got way more places to stick it than most average users. It's not lost, but would be a major effort to reconstruct from archived DVD's. Most of the people I know have no idea how to backup and restore the OS. And nowhere to save the backup if they did. |
#20
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In article , Mike
wrote: Can you explain lifespan in laymen's terms? eventually, an ssd, hard drive or other component will wear out. that's its lifespan. for ssds, it's usually after many petabytes of writes, but that's an expected lifetime, not a guarantee. I don't remember the exact numbers, but terms like MTBF are often misconstrued. IIRC MTBF is the time by which a significant percentage of devices will fail. In aggregate, that number is useful for estimating warranty failures. But for the individual, it's meaningless. Your device is either dead or it is not. MTBF doesn't mean that YOUR device will last that long, or even close to that long. All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? yep, mtbf isn't that useful for a single unit. How does TBW inform the single user? And what does it measure anyway? SMART reports system writes. Does that include write amplification? smart reports a lot of stuff, including bytes written, reallocated blocks, uncorrectable errors, hours used and much more. here's what intel sata ssds report: https://www.intel.com/content/dam/su.../solid-state-d rives/Intel_SSD_Smart_Attrib_for_SATA.PDF If you don't abuse it mechanically or thermally, a HDD has few sources of wearout. except for the moving parts, and there's a lot of them... hard drives either fail early on (due to a manufacturing defect) or they fail after a few years, when parts start to wear out. The SSD has a GUARANTEED source of wearout. You are mechanically abusing the cells at the micro level and taking epic measures to spread that wearout and recover from inevitable cell failure with error correction. It's a leaky bucket that you keep patching with duct tape. When you run out of duct tape, you're done...maybe... reading and writing to a hard drive is abusing the moving parts, which have incredibly tight tolerances... nothing lasts forever. there is no need for that or any other lifespan utility since it's exposed in smart and the ssd will likely outlast the device it's in anyway, longer than any mechanical hard drive would have. If you buy new computers and update regularly, I believe that's the case. For those of us who buy the computers you discarded, thank you very much, and use them for another decade, not so much. used hard drives and ssds just means that the expected life will be shorter. ssds are still more reliable, other than the early ones that were buggy, which might be found in older used equipment. but in the unlikely event it does fail, replace it, restore from backup. no big deal. certainly not worth obsessing over. That's easy to say, but how many actually do that. sadly, not many overall, although it should be quite high for those reading usenet... and something doesn't have to fail to lose data. it could be lost to fire, flood, theft, etc., which is why *offsite* backups are important. a backup won't do much good if it's next to the computer and the house burns down, destroying both... I frequently image 22GB of C: drive. But there's a terabyte of stuff on there that isn't backed up regularly. I've got nowhere to put it. And I've got way more places to stick it than most average users. It's not lost, but would be a major effort to reconstruct from archived DVD's. buy a terabyte hard drive. problem solved. you say you buy used stuff. it's *very* common to see used 1-2 tb drives for cheap ($10-20, typically) because people have upgraded to larger capacity drives. usually they're in relatively good shape too. 500g and smaller are *really* cheap. very few people want something that small anymore. Most of the people I know have no idea how to backup and restore the OS. And nowhere to save the backup if they did. that's one reason why cloud backup services are very popular. they're easy to set up and they work with little to no fuss. |
#21
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On 1/5/2019 2:19 AM, Mike wrote:
I don't remember the exact numbers, but terms like MTBF are often misconstrued.Â* IIRC MTBF is the time by which a significant percentage of devices will fail.Â* In aggregate, that number is useful for estimating warranty failures.Â* But for the individual, it's meaningless.Â* Your device is either dead or it is not. MTBF doesn't mean that YOUR device will last that long, or even close to that long.Â* All it means is that, if you have a large number of them, about half of them will die before MTBF. No, that is not what MTBF means. snip The SSD has a GUARANTEED source of wearout.Â* You are mechanically abusing the cells at the micro level and taking epic measures to spread that wearout and recover from inevitable cell failure with error correction.Â* It's a leaky bucket that you keep patching with duct tape. When you run out of duct tape, you're done...maybe... Yes, and under normal use, how many years does it take to get to wearout? (Only) You can make the computations for how you use you drives. If the answer is 25-50 years, is SSD wearout really an issue? snip I frequently image 22GB of C: drive.Â* But there's a terabyte of stuff on there that isn't backed up regularly.Â* I've got nowhere to put it. That would be by your choice. External drives are readily available. And I've got way more places to stick it than most average users. It's not lost, but would be a major effort to reconstruct from archived DVD's. Restoring from a proper backup would be less effort. Most of the people I know have no idea how to backup and restore the OS. And nowhere to save the backup if they did. Ignorance is a poor excuse. Backup tools are readily available. |
#22
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Mike wrote:
Can you explain lifespan in laymen's terms? http://nomtbf.com/2015/05/determine-...-distribution/ "I find MTBF oversimplifies failure data to the point of making the summary without value." Rather than ogling the value, you're supposed to use the number to work out how many spares to keep in your stock cabinet. Maybe I give you a number, and you work out "I need to keep five spares in the cabinet for this year, to cover the possible failures from the hundred of these I just installed". That would be a reason for seeking an MTBF number. The number assumes some sort of random failures. To be valid, the rate of failure has to have "just the right shape", to justify putting an MTBF in print. Because no product lasts long enough to give actual "field data", MTBF is a calculated estimate (an extrapolation of sorts). Field data (motor failures, head failures) can be fed into the calculation to make it "semi-realistic". Field data would be preferred if we could get it. ******* SSDs wear out. (That's "different" than MTBF.) TLC flash can be written 3000 times per location. The drive uses "mapping" inside, to put LBAs at random locations, such that near the end of drive life, one location is written 2999 times, another written 3001 times. The wear is "leveled", by not having a linear 1:1 relationship between external LBA and internal storage address. Drive brands have different policies, when they hit 3000. Some brands, the drive *bricks* the instant it hits 3000. For *each brand*, you have to research what that policy is. As it affects your backup practices. With a sloppy drive, you could be a sloppy SSD owner. With a "precise" drive, you'd better be "wide awake" if you don't want to suffer data loss. You come in one day, turn on the computer and *boink*, no boot drive. Toast. Now, what did I do with my backup ? And imagine how you feel, when you got that tablet for $100 on Black Friday and the tablet goes *boink* and the eMMC storage is soldered to the motherboard. ******* SSDs can have uncorrectable errors just like an HDD can. You would expect this to be worse, after you surpass 3000 writes per cell. And, there was at least one TLC based drive, that the cells became "mushy" and the read rate of the drive slowed down, because all of the written sectors after three months, needed error correction (the drive was not even remotely near end of life!). Modern flash might require 50 extra bytes of storage for the error corrector, over and above the 512 bytes of user data. Storage is needed for 562 bytes of data, to "represent" the user 512 bytes of data. The high overhead tells you how "spongy" the storage is. Eons ago, hard drives used the Fire Polynomial. A 512 byte sector might only have 11 bits of overhead (I can no longer find a reference to this period in history and I'm using my own feeble recollection of the number). Just like SSDs, changes to coding methods at the head level, the usage of PRML, mean that HDDs also have a heavy error corrector overhead today. But I've not seen any hints as to how that has changed, versus where SSDs started out. When the SLC SSDs came out, they didn't need 50 bytes overhead per 512 byte sector, and the number was somewhat less. The Fire Polynomial excelled at independent bit errors. This means, on the hard drives they were used on, the coding method caused little "burst like" error side effects. Each polynomial used for error detection and correction has a set of math properties that go with it. You must select the correct one, for the situation. A trivial change to how the hardware works, could wreak havoc for the "polynomial guy" :-) And those guys do work hard. Somebody at work who did a silicon block to do error correction, it took several months to finish his design. And the "skills" he learned doing that, helped him find a job at another company :-) Bonus. An example of "belt and suspenders" method, is three dimensional Reed Solomon on CDs. This provides excellent error correction, even allowing the user to take a nail and make "radial scratches" on the surface. But the method only allows certain kinds of scratches to be handled well. Generally, CDs fail because the laser cannot track the groove, not because Reed Solomon cannot correct the error-filled data. One other thing, is that even when a CD is prepared with three dimensional protection, the "corrector" in the drive might only be using two dimensions. It may not actually possess the ability to use all available info when correcting on reads. It's possible Reed Solomon is being used in the SSD case too. PDF page 60 of 66 here, gives a table of correction method versus flash type. A method can only be selected, if it's known errors are "scattered" or "burst", on actual devices, as the methods are good at different things. Some methods are complex enough, they're done on the SSD processor (firmware), rather than with a dedicated logic block (the way it should be done). https://repositories.lib.utexas.edu/...pdf?sequence=1 Paul |
#23
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On 1/5/2019 10:33 PM, Jim H wrote:
On Sat, 5 Jan 2019 00:19:37 -0800, in , Mike wrote: MTBF doesn't mean that YOUR device will last that long, or even close to that long. All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? You can wish that's what the MTBF figure tells you, but in reality the probability of your device lasting as long as the MTBF figure is more like 37%. Only if you assume the failure rate is constant over time and there are no wear out mechanisms. |
#24
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On 1/6/2019 11:16 AM, Wolf K wrote:
On 2019-01-06 08:31, joe wrote: On 1/5/2019 10:33 PM, Jim H wrote: On Sat, 5 Jan 2019 00:19:37 -0800, in , Mike wrote: MTBF doesn't mean that YOUR device will last that long, or even close to that long.Â* All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? You can wish that's what the MTBF figure tells you, but in reality the probability of your device lasting as long as the MTBF figure is more like 37%. Only if you assume the failure rate is constant over time and there are no wear out mechanisms. Seems to me that MTBF is testable, no assumptions required. I expect the published figure(s) to summarise the test results. Where are the stats? So, how would you test an SSD with 1.5 million hour MTBF? |
#25
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Wolf K wrote:
On 2019-01-06 14:01, joe wrote: On 1/6/2019 11:16 AM, Wolf K wrote: On 2019-01-06 08:31, joe wrote: On 1/5/2019 10:33 PM, Jim H wrote: On Sat, 5 Jan 2019 00:19:37 -0800, in , Mike wrote: MTBF doesn't mean that YOUR device will last that long, or even close to that long. All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? You can wish that's what the MTBF figure tells you, but in reality the probability of your device lasting as long as the MTBF figure is more like 37%. Only if you assume the failure rate is constant over time and there are no wear out mechanisms. Seems to me that MTBF is testable, no assumptions required. I expect the published figure(s) to summarise the test results. Where are the stats? So, how would you test an SSD with 1.5 million hour MTBF? The converse question is, How do you know the SSD's MTBF is 1.5 Mh? IOW, the claimed MTBF is based on some testing. What's tested? And how are those test results converted in MTBF numbers? I know that when mechanical testing doesn't result in failure in a reasonable time, wear is used as an indicator of time-to-failure. Is there something similar for SSDs? Best, https://serverfault.com/questions/64...n-failures-ssd "MTTF of 1.5 million hours sounds somewhat plausible. That would roughly be a test with 1000 drives running for 6 months and 3 drives failing. The AFR would be (2* 6 months * 3)/(1000 drives)=0.6% annually and the MTTF = 1yr/0.6%=1,460,967 hours or 167 years. A different way to look at that number is when you have 167 drives and leave them running for a year the manufacturer claims that on average you'll see one drive fail. " Since "the number" for HDD and SSD is so close, you have to suspect there's something wrong with the methodology or notion. One device is just a circuit board with some LSI on it. The other device has a circuit board plus mechanical bits. Paul |
#26
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"Paul" wrote in message
... Since "the number" for HDD and SSD is so close, you have to suspect there's something wrong with the methodology or notion. One device is just a circuit board with some LSI on it. The other device has a circuit board plus mechanical bits. If the MTBF is very simliar for both SSD and HDD, it suggests that the control and interface logic (the part that is common to both types) is the weakest link, which hides any other failures in the data storage mechanism (solid-state or spinning disc and head assembly). |
#27
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On 1/6/2019 11:25 AM, Wolf K wrote:
On 2019-01-06 14:01, joe wrote: On 1/6/2019 11:16 AM, Wolf K wrote: On 2019-01-06 08:31, joe wrote: On 1/5/2019 10:33 PM, Jim H wrote: On Sat, 5 Jan 2019 00:19:37 -0800, in , Mike wrote: MTBF doesn't mean that YOUR device will last that long, or even close to that long.Â* All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? You can wish that's what the MTBF figure tells you, but in reality the probability of your device lasting as long as the MTBF figure is more like 37%. Only if you assume the failure rate is constant over time and there are no wear out mechanisms. Seems to me that MTBF is testable, no assumptions required. I expect the published figure(s) to summarise the test results. Where are the stats? So, how would you test an SSD with 1.5 million hour MTBF? The converse question is, How do you know the SSD's MTBF is 1.5 Mh? IOW, the claimed MTBF is based on some testing. What's tested? And how are those test results converted in MTBF numbers? I know that when mechanical testing doesn't result in failure in a reasonable time, wear is used as an indicator of time-to-failure. Is there something similar for SSDs? Best, I have not done any MTBF computations since 1980. Back then, it was garbage in/garbage out. The component guys had some basic failure rate numbers. We took the component count for each type, multiplied it by the failure rate and added it all up...GIGO. So, TTL had a rate per chip. The number of pins related to the number of connections. Sockets had dramatically bigger failure numbers than soldered connections. The list is endless. Result was a number that kept the reliability overlords happy. As an engineer, the most important part of it all was the design guidance the PROCESS provided. Don't use sockets, keep temps down, this technology was more reliable than that chip technology, vibration is to be avoided, etc. We did accelerated life testing for relatively short periods, but failures were very rare. And the duration was so short as to be statistically irrelevant. Field failures were often more environmental than anything else. Instrumentation used in a damp, corrosive environment had dramatically higher failure rates. But the MTBF number had no input for that. As for SSD's, the wearout process is known. And the time to failure is short enough that you can actually get some info from testing. It appears that each generation makes the problem worse by cramming more bits into a single cell...then fixing it in software. Wear leveling Data error correction Automatic swapping out of inevitable bad cells Overprovisioning Secret stuff At the cell level, the MTBF is laughably short. Hopefully all the software magic can make the SSD reliable at the macro level. I'd rather they fix the root cause, but that looks like it will have to wait for an innovation in the basic cell operation. If I understand correctly, we're already down to counting electrons on two hands to determine the stored value. I'm amazed it works at all. |
#28
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Wolf K wrote in
: On 2019-01-06 08:31, joe wrote: On 1/5/2019 10:33 PM, Jim H wrote: On Sat, 5 Jan 2019 00:19:37 -0800, in , Mike wrote: MTBF doesn't mean that YOUR device will last that long, or even close to that long.Â* All it means is that, if you have a large number of them, about half of them will die before MTBF. Are you feeling lucky? You can wish that's what the MTBF figure tells you, but in reality the probability of your device lasting as long as the MTBF figure is more like 37%. Only if you assume the failure rate is constant over time and there are no wear out mechanisms. Seems to me that MTBF is testable, no assumptions required. I expect the published figure(s) to summarise the test results. Where are the stats? For newly released products, MTBF is calculated from pre-release test results. These are usually the results of accelerated testing, and can't account for actual in-use numbers. It is modified (sometimes) based on real world experience. To avoid complications most manufacturers just stay with the original MTBF. Reviewers and independent testers try to work with real world data. |
#29
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Mike wrote:
At the cell level, the MTBF is laughably short. But that's not true. If you don't write to a cell, it holds up quite well. When you're not writing the SSD, it should have similar reliability to the odds of the DRAM on your computer going bad. I had a RAM failure once that would serve as an example. Computer crashes. Testing reveals that one chip on the DIMM has gone tristate and it "won't answer the bell" when chip-selected. It returns random data from end to end. Rather than that being the "odds of one bit failing" in the memory array, instead something failed closer to the interface, and the chip was no longer functioning at all. And apparently this is a recognized fault type - it happens often enough to be a "thing". That's why CHIPKILL and nibble wide memory chips are popular (CHIPKILL can correct a four bit error), so if a chip fails entirely, the module has sufficient redundancy to cover for it (error correction in memory controller). Some Enterprise SSDs have RAIN inside, as a foil for this failure mode. On consumer drives, we're "eating" this failure mode (data loss). https://www.micron.com/-/media/clien...f_ssd_rain.pdf Paul |
#30
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On 1/6/2019 1:53 PM, Paul wrote:
Mike wrote: At the cell level, the MTBF is laughably short. But that's not true. If you don't write to a cell, it holds up quite well. We have very different views of reliability. If there's not enough oxygen, just don't breathe, makes about as much sense. 3000 erase-write cycles is a TINY number. The only way that works is if you don't do it. They take Herculean measures to spread the wear and recover from bad data bits. BucketsRus.com Our 5 gallon buckets are full of holes, but you get a free roll of duct tape and a monkey that follows you around patching new holes. And if you only carry a quart at a time, it's likely that most of the contents will arrive at the destination. And they're more expensive than our competitor's quart buckets, so they must be better. Get yours today... Would you rather drive over a bridge made of papier mache in the rain, even tho there was a permanent staff of repair drones? Or a steel/concrete one that didn't require spackle on an hourly basis. I believe in the "fix it in software" concept, but I'd prefer a design that didn't require as much of it. When you're not writing the SSD, it should have similar reliability to the odds of the DRAM on your computer going bad. I'm not buying it. DRAM doesn't have a designed-in failure mode. DRAM fails if the manufacturing process failed and you got one with a latent defect. SSD have DESIGNED-IN failures in a SHORT time pasted over with failure symptom mitigation. Not at all the same thing. I like the analogy that there's probably more horsepower correcting errors on your SSD than it took to get man to the moon. I certainly don't understand the process, but I imagine the SSD write process as shooting bullets thru a wall and hoping that the stuff inside is too big to escape thru the holes...YET. It's not a matter of IF, but WHEN. And the when is predicted at around 3000 bullets. And we shoot a lot more bullets than needed just so we don't shoot this one wall too many times. So, let's make the walls smaller and more fragile so we can have more walls that we're not shooting. What could possibly go wrong? I'm not blind to the fact that magnetic and optical media also require failure mitigation, but I characterize that as a media failure that can be improved with better manufacturing processes. SSD individual cell reliability seems to be decreasing over time. And we're not too far from physical limitations on cell size and thus the amount of redundancy that can be applied using known technology. Ain't progress fun... I had a RAM failure once that would serve as an example. Computer crashes. Testing reveals that one chip on the DIMM has gone tristate and it "won't answer the bell" when chip-selected. It returns random data from end to end. Rather than that being the "odds of one bit failing" in the memory array, instead something failed closer to the interface, and the chip was no longer functioning at all. And apparently this is a recognized fault type - it happens often enough to be a "thing". That's why CHIPKILL and nibble wide memory chips are popular (CHIPKILL can correct a four bit error), so if a chip fails entirely, the module has sufficient redundancy to cover for it (error correction in memory controller). Some Enterprise SSDs have RAIN inside, as a foil for this failure mode. On consumer drives, we're "eating" this failure mode (data loss). https://www.micron.com/-/media/clien...f_ssd_rain.pdf Â*Â* Paul |
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