I dabble in microprocssors such as AVRs and such and they have a flash life of around 40,000 flashes before they are dead.
I was wondering what the "Flash Life" of tablets are. Will there be a time when they will finally burn out?
Now 40,000 flashes are more than anyone would be able to flash this device in a reasonable tablet lifetime before it is obsolete. Just wondering what the number would be.
Since all flash is in the eMMC, firmware flashes count as normal writes. The eMMC is using MLC or even TLC, so we are talking about a few 1000 writes for each cell, distributed over the full capacity by the eMMC's FTL for wear leveling. So let's say 64 GB * 1000 = 64 TB total writes, but this has to be divided by the write amplification factor. It's a bit hard to estimate write amplification due to the primitive controller and FTL - it could even be up to 1000 in the worst case of all random 4 kB writes (each would need to rewrite a full erase block). More realistic may be a factor of 5 to 20 - so let's guess 64 TB / 10 = about 6 TB written in total.
Fascinating question:
Only thing I see are claims from Hynix (formerly Hyundai) that their recent SSD and NAND memory has up to 2,000,000 hours MTBF.
Don't see how this claim would hold water in a real sense....just a calculated guess on the manufacturers part.
Hard to tell when write failure will occur at the lower voltage levels used for eMMC's.
I'd think 40 to 60,000 hours would be more in line.
Thanks _that.
I should be able to burn this thing out in a month or so. LOL J/K.
When flashing does the eMMC get totally erased before writing or are just the addresses used in the code written to the chip? This would determine the life of the chip as a total erase would shorten the life. Am I correct in assuming this or is my understanding all wrong?
Is there a data sheet available for the eMMC used in these devices or is it an ASUS trade secret?
Thats OK, are you talking about actual hours flashing or just the run time of the chip?
Dee Envy said:
Thanks _that.
I should be able to burn this thing out in a month or so. LOL J/K.
When flashing does the eMMC get totally erased before writing or are just the addresses used in the code written to the chip? This would determine the life of the chip as a total erase would shorten the life. Am I correct in assuming this or is my understanding all wrong?
Is there a data sheet available for the eMMC used in these devices or is it an ASUS trade secret?
Thats OK, are you talking about actual hours flashing or just the run time of the chip?
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Ah I was looking at time before failure on Hynix eNAND.
That 2 million hours seemed a bit way out.
Just searching around for a data sheet on the Hynix M26M64002BNR is turning into a dead end.
Everything goes to an HY27 number looks like the chip has been replaced from the maker.
I was hoping I could find actual read\write white paper for the chip.
Dee Envy said:
When flashing does the eMMC get totally erased before writing or are just the addresses used in the code written to the chip?
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Flash memory has 3 operations: erase, write, read.
Magnetic storage has only 2: (over)write, read.
So, to overwrite something in flash memory, an erase operation is always necessary. And this operation has a granularity in the megabyte range - that's why random 4k writes are so slow.
If you want to know how flash cards work, read this:
https://wiki.linaro.org/WorkingGroups/KernelArchived/Projects/FlashCardSurvey
Thanks for the link, _that.
There's some good reading there.:good:
Related
I did a search but I only have a phone to do this from so hopefully I didn't miss it.
Is it possible to make ram run off of the SDCard in a new partition (or even a current partition) simalar to Readyboost for vista? With all these home screen apps taking up so much RAM is would be helpful.
I am what you would call an advanced noob at this so don't flame me if I'm totally off.
I don't believe android supports something like this, this is sort of like Virtual Memory in Windows. However, the effectiveness of this isn't very good, moreover, the speed of the SD card or even support for this feature is... unknown. So, for now, I'm going to have to say I don't think so.
http://forum.xda-developers.com/showthread.php?t=483110&highlight=swap
Yeah, it's in the market now too. I haven't tried it out though, I don't want to make my microSD card last even less now... =P
axion68 said:
http://forum.xda-developers.com/showthread.php?t=483110&highlight=swap
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Thank you for that.
amgupt01 said:
Yeah, it's in the market now too. I haven't tried it out though, I don't want to make my microSD card last even less now... =P
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Any idea how much less?
mmafighter077 said:
Any idea how much less?
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Linux swap partitions aren't designed for flash memory like Readyboost is. Microsoft says Readyboost is designed to make your memory last at least 10 years with moderate use, but Linux swap might stress it more. MicroSDs are really cheap though.
nm page didn't load right, i thought i was the first post with useful info.
mmafighter077 said:
Any idea how much less?
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It should still last you years.
Each sector on flash media can be written to something like 10,000 times. After that's worn out, I believe it just ignores that sector. Meaning when your mem stick starts dying, you'll just have less space available to you.
I currently run my notebook with a Compact Flash card in the notebooks built in CF slot, and run my swap file on that. It's been a while, and it still hasn't died.
It's quite a long time - a sector isn't written 10,000 times sequentially, the hardware in the chip moves the writes around to avoid wearing out any single element (wear levelling), and if any single element does go it'll just ignore it, as you mentioned.
Any modern SD is likely to outlive the phone, basically. I've got entire computers running off SD and I've never had a failure (hard drives fail way more often, due to their mechanical nature).
my android is running off a SD card.
anyone please exxplain what is 'NAND'?
I think it is short for Nandroid. Which is a backup made by either Titanium backup,CWM or another program that can do advanced backups.
Sent from my GT-N7000 using Tapatalk
NAND flash memory
NAND flash memory is a type of non-volatile storage technology that does not require power to retain data.
There are two types of flash memory, NAND and NOR. The names refer to the type of logic gate used in each memory cell. (Logic gates are a fundamental building block of digital circuits). NOR flash was first introduced by Intel in 1988. NAND flash was introduced by Toshiba in 1989.
The two chips work differently. NAND has significantly higher storage capacity than NOR. NAND flash has found a market in devices to which large files are frequently uploaded and replaced. MP3 players, digital cameras and USB drives use NAND flash. NOR flash is faster, but it's also more expensive. NOR is most often used in mobile phones.
Some devices use both NAND and NOR. A pocket PC, for instance, may use embedded NOR to boot up the operating system and a removable NAND card for all its other memory/storage requirements. NAND has a finite number of read-write cycles, though the total number continues to increase with each generation of chips. If the NAND card wears out, the user simply buys a new one and the device continues to function. By passing the expense of additional storage on to the consumer, manufacturers have been able to lower the price of consumer electronic devices significantly.
An important goal of NAND flash development has been to reduce the cost per bit and increase maximum chip capacity so that flash memory can compete with magnetic storage devices like hard disks. New developments in NAND flash memory technology are making the chips smaller, increasing the maximum read-write cycles and lowering voltage demands. Such improvements will continue make the technology even more common in laptops and thin client desktop computers.
MoPhoACTV Initiative
Thank you, very interesting reading.
Thanx everybody for the info, appreciate it so much... looking for nand for htc hd mini...
solleh.mc said:
Thanx everybody for the info, appreciate it so much... looking for nand for htc hd mini...
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That makes no sense. What exactly do you think it is you are looking for? Memory? SD card? Backup?
DirkGently said:
That makes no sense. What exactly do you think it is you are looking for? Memory? SD card? Backup?
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this is what im talking about...
http://forum.xda-developers.com/showthread.php?t=1455555
Photonic CM 7.2; No GPS
I'd been using this rom since day 1 Schlund upload it at Xda-Developer.
Until now my GPS dont working at all, anyone can help me out?
regards...
if i make a second partition in the last zone of an sd, after too many write, the primary partition will still works and only the second partition will blow up or it will broke the entire sd?
washwash said:
if i make a second partition in the last zone of an sd, after too many write, the primary partition will still works and only the second partition will blow up or it will broke the entire sd?
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Can be anything bro
Sent from my LG-X160 using XDA Free mobile app
i'm asking because i want to use swap, but if the swap partition will destroy only the partition zone instead of the entire sd...i will choose the partition instead of the swap file
washwash said:
i'm asking because i want to use swap, but if the swap partition will destroy only the partition zone instead of the entire sd...i will choose the partition instead of the swap file
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i dont believe there is a definitive answer to your question.
a sd card is flash memory, so theoretically, it should only burn out the sectors in the partition, but there is no guarantee the damage wouldnt unexpectedly cause the whole card to be dead.
i would go with the partition. at least you have a chance at only damaging part of the card, instead of all of it for sure.
washwash said:
if i make a second partition in the last zone of an sd, after too many write, the primary partition will still works and only the second partition will blow up or it will broke the entire sd?
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Physical Damage
First, cards can be actually physically broken. You can bend them in half pretty easily if you try, but in general they're actually pretty resilient. Many are effectively water-proof even if not marketed that way. I've sent cards through the laundry, and once I dropped one full of precious baby photos right into hot coffee — no problem! Now, I wouldn't recommend pushing your luck, but if you're careful, this is unlikely.
Electrostatic discharge could also damage the electronics, although again most cards are surprisingly well-resistant. (Try to intentionally destroy a card with static and your success rate will be low.)
Flash isn't particularly light-sensitive, so airport x-rays aren't a real risk (longer exposure to high-energy x-rays is another story). It's also surprisingly heat-resistant — the plastic housing is probably at more risk than the memory itself.
Filesystem and File Corruption
Physical damage is at the most basic level. At the higher end, you can have corruption and data loss without anything fundamentally going wrong. The firmware in cameras and card readers (that is, the mini-os and software that runs on the device) can make mistakes, or be caught in situations it can't handle.
The most obvious is that you can mess things up if you pull out the card while trying to write to it. Don't do that. (And remember that with caching, that can happen quite a while after you think the data transfer is done.) With SD or Compact Flash cards, it's usually reasonably safe to remove the card from a reader while it's mounted for read access; beware that if you happen to have an xD card device that this is not safe.
A bug could happen in deleting files, or if the card fills up. And, it's theoretically possible that if you format the card on a computer conflicting filesystem bugs will cause issues.
Presuming you avoid the yank-the-card-out scenario, and don't have a hardware failure, these are also pretty rare, because the filesystem implementations used in cameras have been around for a long time and are very well tested.
It's also possible that bad cables, bad USB ports, or problems in the computer itself could corrupt files on transfer. Trying again on another system is always a good first diagnostic.
In all of these cases, the card itself is really fine — reformat and you can use it again.
Bad Blocks
Then, there's the SD card really going corrupt.
This happens in two major ways:
Manufacturing Defects
There's a lot of pressure to produce small, cheap, high-capacity devices. In order to do this, manufacturers have learned to not worry about perfection, and ship devices with something like 2-5% of the memory already bad, right out of the factory. These initial bad blocks are masked out and shouldn't affect anything, but actually do have a long term effect — see below.
And it's possible that a particular card will have a lot more than it's supposed to, including blocks which weren't properly masked out. This is much more likely with cheap cards.
Accumulated Failure
Flash memory inherently has a limited number of write/erase cycles. Inevitably, electrons get trapped where they're not wanted, and the voltage levels shift, eventually causing read or write failure. Any given bit of flash memory is specified for a certain number of cycles before failure, but really it's a random process and there could be a problem long before the numbers would predict on average.
Coping Mechanisms
Because these things are inevitable, SD cards are designed to minimize the damage. In addition to the masking out of bad blocks initially, they detect and mask out new bad blocks as they appear. They're made with excess capacity initially, and as blocks wear out, spare blocks are transparently substituted, so everything keeps working. The flash card's built-in controller will use error correction to prevent the errors from corrupting data as they occur.
But, cheaper cards may have less sophisticated error correction, and are likely to have less spare capacity for covering up for bad blocks.
Flash devices also use wear leveling, so that writes are spread across the whole device, not just always using the same area over and over. Here again, cheap cards may do a worse job of this.
I'm trying to figure out how damaging repeatedly formatting and flashing a phone can be. I've managed to figure out that solid state drives have a limited number of "write cycles" before failing, but I'm unsure if the internal SD in Android devices is generally considered an SSD, I know some phones use eMMC which is different.
I'm also unsure if formatting and then flashing would be considered one full write cycle, more than, or less than one full write cycle. Doesn't "write cycle" mean filling every block on the SSD?
I was hoping someone with more knowledge in this could at least point me in the right direction. I'm just trying to figure out (roughly) how much you could format/flash a phone before it would start to read/write slower or produce errors.
Thanks for taking the time to read, and for any help you can offer!
Just did a quick search, and came across this:
http://www.howtogeek.com/196541/emmc-vs.-ssd-not-all-solid-state-storage-is-equal/
"eMMC is typically a type of storage found in portable electronic devices like cell phones and digital cameras. With a push toward super-cheap $99 tablets and $199 laptops that need solid-state storage and not mechanical drives, cheap tablets and laptops are also being built with eMMC drives."
Thanks for the link! I was looking at that, some good info! It sounds like non-eMMC storage in a phone would be considered an SSD, from what they said.
What I'm really curious about is how a format/flash relates to a write cycle, how many cycles it would use up, etc.
I have used a Samsung Galaxy Note 3 as my daily phone for 4 years. It had a previous owner and is 7.5 years old (yes, it is somehow usable without lag on custom ROMs). I am wondering if I am in danger of the eMMC flash storage failing and if I should start backing the phone up semi-regularly. I heard eMMC lifespan is typically 3-5 years but the phone has been operating beyond that. Also, are there signs of failure or would this be sudden death?
Thanks
eMMC devices use wear leveling techniques to work around erase/write limitations by arranging data and distributing writes evenly across the system (so no single block fails due to intensive writes).
The life of eMMC depends on amount of writes and write patterns used: the less data get written onto eMMC the slower the eMMC wears, and writing data frequently in small chunks wears the eMMC faster than writing the same amount of data less frequently and in larger chunks.