If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Tools to measure flash drive life remaining?
I've read lots of times that USB flash drives have a limit of like 10000
write/erase cycles. Is the limit just an approximation and sectors simply fail when they fail and there is no way to tell when that will occur exactly? Or is there something stored internally by the manufacturer that says "this sector has been written to x number of times so it won't be used again"? Are there any tools that will help determine the health of a flash drive and the remaining number of write/erase cycles? Thanks |
#2
|
|||
|
|||
Tools to measure flash drive life remaining?
Burma wrote:
I've read lots of times that USB flash drives have a limit of like 10000 write/erase cycles. Is the limit just an approximation and sectors simply fail when they fail and there is no way to tell when that will occur exactly? Or is there something stored internally by the manufacturer that says "this sector has been written to x number of times so it won't be used again"? Are there any tools that will help determine the health of a flash drive and the remaining number of write/erase cycles? Thanks There is no limit. A junction may fail after 100 write/erase cycles. It may not fail until after at trillion cycles. The 1,000,000 (not 10K) cycle count is an *average* for MTBF (mean-time between failures) spec. There is no way to know the junction will fail until it does. The maker includes additional memory to use to remap (or mask) the failures. If there are enough failures, this additional memory gets used up until there is no recovery for future failures. The junctions die due to oxide stress. As there are more failures, there are more redirects to mask the failures, and this redirection makes the device slower. Eventually it catastrophically fails and you have to replace the entire device. 1,000,000 MTBF sounds high but not if, say, you use the flash module for pagefile space that gets written thousands of times an hour during use of the OS and apps. Below is what I wrote before when someone was thinking of using Flash memory as a high-speed cache for the pagefile (instead of the hard drive) or to use Flash memory with the new Vista ReadyBoost feature to add it to the system memory (although Flash memory is far slower). That it works doesn't mean it is a good choice. ---------- Don't be misled that electronics are infallible. Just because a USB thumb drive uses flash memory doesn't mean it won't wear out. They can only endure a maximum number of writes or erases. Flash memory can only be flashed so many times. Although electronic, they wear out. How often have you written files (or deleted them or done anything to update the flash drive)? If you are using a program that updates its files on the flash drive, remember that all those updates count against the endurance of the device. Some apps could produce several thousand updates per minute and do so as long as the app is running. Using Flash memory for Vista's ReadyBoost as a disk buffer means generating write cycles at a far greater rate and number than by a user that saves, edits, or deletes music or data files. In Windows versions without ReadyBoost, some users will use Flash memory for pagefile space but the number of writes to the pagefile are very high and will accelerate when the Flash memory fails. Write/erase endurance specs are usually hard to find and rarely divulged by the device makers (so you have to read articles by the flash memory manufacturers but that will tell you the endurance of the chip, not what masking algorithm is employed by the flash drive manufacturer that used that flash chip). Typical MTBF for Flash memory is one million cycles. Sounds high when YOU are the one creating, editing, or deleting files but that is a small change volume for disk buffer or pagefile usage. "Like all flash memory devices, flash drives can sustain only a limited number of write/erase cycles before failure. In normal use, mid-range flash drives currently on the market will support several million cycles, although write operations will gradually slow as the device ages" (http://en.wikipedia.org/wiki/Keydrive). "Flash memory has a finite number of erase-write cycles (most commercially available flash products are guaranteed to withstand 1 million programming cycles) so that care has to be taken when moving hard-drive based applications" (http://en.wikipedia.org/wiki/Flash_memory). Flash drives should NOT be used for permanent storage and any files placed on them should be non-critical files (i.e., you can afford to lose them the same day you put them onto the flash drive). Just like with a hard drive, anything you put onto a flash drive - if important to you - should be backed up to provide a second copy. Flash drives are less prone to physical abuse than hard drives, but then your hard drive, after installed, receives little physical abuse whereas you are subjecting the flash drive to static, dirt, wear from insertion/extraction, physical shock, and other environmental factors. Unlike your system or video RAM, flash memory does wear out as it suffers from electric field stress (thin oxide stress). Over time, oxide stress from repeated program and erase operations may degrade the gate oxide layer to cause the transistor to malfunction. This contributes to faulty operation of the flash memory device. Accordingly, there is a need for a method of detecting a transistor error caused by the degradation of the gate oxide layer. That is why these devices will incorporate fault-tolerant schemes to mask the failures. More masking (or remapping) as more errors occur results in more redirects that slow performance, and there is usually a maximum (spare space used for the masking) after which the device catastrophically fails. Performance with Flash memory is unbalanced in that reading from the device is faster than writing to it. ReadyBoost or putting the pagefile on Flash memory doesn't speed up Vista by much and often slows it down. It only helps if the sectors for the data are scattered to different cylinders on the hard disk for a speed boost of around 4 to 6%. If the disk has been defragmented or the data is otherwise serially retrieved from the hard disk, Flash drives actually slow performance. Flash drives have much slower throughput than hard drives. Flash memory has a bandwidth of around 3.5MB/s (28Mb/s) for 4KB transfers and around 2.5MB/s (20Mb/s) for 512KB transfers. An ATA-100 IDE hard drive can sustain much higher average transfer rates without even considering its burst mode. Only if the hard disk's heads have to do a lot of bouncing between cylinders might Flash memory then outperform a hard disk. What most users report as the noticed speedup by using Flash memory for the pagefile is a slightly shorter time to load applications, but a faster spinning hard disk or one that uses perpendicular recording to pack the bits closer together to effect a higher transfer rate do that, too. You gain little overall speedup by using Flash for pagefile space but incur a greater liability to system stability with a device that will slowdown over continued high usage due to masking and will eventually catastrophically fail. ReadyBoost is a problem waiting to happen, and when it happens (not if it happens) becomes shorter and shorter. The fuse will burn out. Using Flash memory as pagefile space means eventually you get a hung or crashed OS or memory corruption errors which means losing data (or worse in saving the corrupted data). Flash memory is significantly slower than physical system RAM and can only provide a tiny speedup for highly fragmented files on the hard disk. Rather than waste money on a Flash thumb drive for ReadyBoost or for pagefile space, spend it on more system RAM or get a faster hard disk. You should not incorporate an obviously weak component (e.g., Flash) within your mass storage subsystem. Just because Flash memory drives are newer doesn't mean they are ideal choices to supplant older technology. There are good uses for Flash memory, as in USB thumb drives or use in digital cameras, but don't use it to supplant real system memory or the highly stressed pagefile on the hard drive. ---------- |
#3
|
|||
|
|||
Tools to measure flash drive life remaining?
OK, thanks for that info. Any way to tell how many failures or bad sectors
or whatever are on a flash drive? VanguardLH wrote, On 4/30/2009 4:01 PM: Burma wrote: I've read lots of times that USB flash drives have a limit of like 10000 write/erase cycles. Is the limit just an approximation and sectors simply fail when they fail and there is no way to tell when that will occur exactly? Or is there something stored internally by the manufacturer that says "this sector has been written to x number of times so it won't be used again"? Are there any tools that will help determine the health of a flash drive and the remaining number of write/erase cycles? Thanks There is no limit. A junction may fail after 100 write/erase cycles. It may not fail until after at trillion cycles. The 1,000,000 (not 10K) cycle count is an *average* for MTBF (mean-time between failures) spec. There is no way to know the junction will fail until it does. The maker includes additional memory to use to remap (or mask) the failures. If there are enough failures, this additional memory gets used up until there is no recovery for future failures. The junctions die due to oxide stress. As there are more failures, there are more redirects to mask the failures, and this redirection makes the device slower. Eventually it catastrophically fails and you have to replace the entire device. 1,000,000 MTBF sounds high but not if, say, you use the flash module for pagefile space that gets written thousands of times an hour during use of the OS and apps. Below is what I wrote before when someone was thinking of using Flash memory as a high-speed cache for the pagefile (instead of the hard drive) or to use Flash memory with the new Vista ReadyBoost feature to add it to the system memory (although Flash memory is far slower). That it works doesn't mean it is a good choice. ---------- Don't be misled that electronics are infallible. Just because a USB thumb drive uses flash memory doesn't mean it won't wear out. They can only endure a maximum number of writes or erases. Flash memory can only be flashed so many times. Although electronic, they wear out. How often have you written files (or deleted them or done anything to update the flash drive)? If you are using a program that updates its files on the flash drive, remember that all those updates count against the endurance of the device. Some apps could produce several thousand updates per minute and do so as long as the app is running. Using Flash memory for Vista's ReadyBoost as a disk buffer means generating write cycles at a far greater rate and number than by a user that saves, edits, or deletes music or data files. In Windows versions without ReadyBoost, some users will use Flash memory for pagefile space but the number of writes to the pagefile are very high and will accelerate when the Flash memory fails. Write/erase endurance specs are usually hard to find and rarely divulged by the device makers (so you have to read articles by the flash memory manufacturers but that will tell you the endurance of the chip, not what masking algorithm is employed by the flash drive manufacturer that used that flash chip). Typical MTBF for Flash memory is one million cycles. Sounds high when YOU are the one creating, editing, or deleting files but that is a small change volume for disk buffer or pagefile usage. "Like all flash memory devices, flash drives can sustain only a limited number of write/erase cycles before failure. In normal use, mid-range flash drives currently on the market will support several million cycles, although write operations will gradually slow as the device ages" (http://en.wikipedia.org/wiki/Keydrive). "Flash memory has a finite number of erase-write cycles (most commercially available flash products are guaranteed to withstand 1 million programming cycles) so that care has to be taken when moving hard-drive based applications" (http://en.wikipedia.org/wiki/Flash_memory). Flash drives should NOT be used for permanent storage and any files placed on them should be non-critical files (i.e., you can afford to lose them the same day you put them onto the flash drive). Just like with a hard drive, anything you put onto a flash drive - if important to you - should be backed up to provide a second copy. Flash drives are less prone to physical abuse than hard drives, but then your hard drive, after installed, receives little physical abuse whereas you are subjecting the flash drive to static, dirt, wear from insertion/extraction, physical shock, and other environmental factors. Unlike your system or video RAM, flash memory does wear out as it suffers from electric field stress (thin oxide stress). Over time, oxide stress from repeated program and erase operations may degrade the gate oxide layer to cause the transistor to malfunction. This contributes to faulty operation of the flash memory device. Accordingly, there is a need for a method of detecting a transistor error caused by the degradation of the gate oxide layer. That is why these devices will incorporate fault-tolerant schemes to mask the failures. More masking (or remapping) as more errors occur results in more redirects that slow performance, and there is usually a maximum (spare space used for the masking) after which the device catastrophically fails. Performance with Flash memory is unbalanced in that reading from the device is faster than writing to it. ReadyBoost or putting the pagefile on Flash memory doesn't speed up Vista by much and often slows it down. It only helps if the sectors for the data are scattered to different cylinders on the hard disk for a speed boost of around 4 to 6%. If the disk has been defragmented or the data is otherwise serially retrieved from the hard disk, Flash drives actually slow performance. Flash drives have much slower throughput than hard drives. Flash memory has a bandwidth of around 3.5MB/s (28Mb/s) for 4KB transfers and around 2.5MB/s (20Mb/s) for 512KB transfers. An ATA-100 IDE hard drive can sustain much higher average transfer rates without even considering its burst mode. Only if the hard disk's heads have to do a lot of bouncing between cylinders might Flash memory then outperform a hard disk. What most users report as the noticed speedup by using Flash memory for the pagefile is a slightly shorter time to load applications, but a faster spinning hard disk or one that uses perpendicular recording to pack the bits closer together to effect a higher transfer rate do that, too. You gain little overall speedup by using Flash for pagefile space but incur a greater liability to system stability with a device that will slowdown over continued high usage due to masking and will eventually catastrophically fail. ReadyBoost is a problem waiting to happen, and when it happens (not if it happens) becomes shorter and shorter. The fuse will burn out. Using Flash memory as pagefile space means eventually you get a hung or crashed OS or memory corruption errors which means losing data (or worse in saving the corrupted data). Flash memory is significantly slower than physical system RAM and can only provide a tiny speedup for highly fragmented files on the hard disk. Rather than waste money on a Flash thumb drive for ReadyBoost or for pagefile space, spend it on more system RAM or get a faster hard disk. You should not incorporate an obviously weak component (e.g., Flash) within your mass storage subsystem. Just because Flash memory drives are newer doesn't mean they are ideal choices to supplant older technology. There are good uses for Flash memory, as in USB thumb drives or use in digital cameras, but don't use it to supplant real system memory or the highly stressed pagefile on the hard drive. ---------- |
#4
|
|||
|
|||
Tools to measure flash drive life remaining?
Burma wrote:
OK, thanks for that info. Any way to tell how many failures or bad sectors or whatever are on a flash drive? Please do not top-post. Your answer belongs after (or intermixed with) the quoted material to which you reply, after snipping all irrelevant material. See the following links: http://www.catb.org/~esr/faqs/smart-questions.html http://www.caliburn.nl/topposting.html http://www.netmeister.org/news/learn2quote.html http://cfaj.freeshell.org/google/ (taming google) http://members.fortunecity.com/nnqweb/ (newusers) -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: http://cbfalconer.home.att.net Try the download section. |
#5
|
|||
|
|||
Tools to measure flash drive life remaining?
Burma wrote:
OK, thanks for that info. Any way to tell how many failures or bad sectors or whatever are on a flash drive? I haven't heard of a tool. The software-based memory testers that I've seen are simply for measuring the usability of the device and possibly its performance. They measure what is measurable from the external interface to the device and not even to the components used to build it. The remapping or wear-levelling logic is built into hardware so it may not be visible using the normal external interface or even through firmware. It was designed to be invisible. That I haven't heard of such a utility (because I haven't bothered to look for one) doesn't mean one doesn't exist. However, many low-level hardware testers require test points on the PCB, chip, or die. That is, what you can generate for test patterns or code execution at die level may not be available at chip level, and chip level tests may not be possible at card level tests, and card level tests may not be possible using the instruction interface to the device. I'm sure Googling would find *what* you want but not at a *price* that you would be willing to pay or could ever manage to pay. Since there's nothing I can do about a Flash memory device other than to wait until it catastrophically fails, there doesn't seem to be much point in obtaining some guess as to when it might fail. When kaput, buy another one. Knowing how many failures there have been won't let you know just when the device as a whole will catastrophically fail. I might start wondering about the survivability of the device if I notice a significant performance loss (due to all the remapping) but then I don't use Flash memory devices as system memory or as a mass storage subsystem but merely as temporary storage. You might find something by searching on articles about failure prediction, like: http://www.google.com/search?hl=en&q...2 Bpredicting http://www.google.com/search?hl=en&q...%2 2+%2Bflash |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Diagnostic tools for Quantum IDE Hard Drive? | Ian R | Storage (alternative) | 2 | October 18th 07 10:47 PM |
Hard drive performance - how to measure | Scott | Homebuilt PC's | 11 | February 6th 07 06:37 PM |
?? Toner cartridge weight as measure of remaining capacity | Salvatore | Printers | 3 | March 17th 05 04:09 AM |
Looking for tools to restore deleted images from compact flash media | Ron | General Hardware | 0 | April 6th 04 09:33 AM |
Backup App to Drive Sony GY-8240 - Show Media Remaining | Edmunde Lee | Storage (alternative) | 0 | September 23rd 03 05:07 PM |