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Flash Destroyer Tests Limit of Solid State Storage
An anonymous reader writes "We all know that flash and other types of solid state storage can only endure a limited number of write cycles. The open source Flash Destroyer prototype explores that limit by writing and verifying a solid state storage chip until it dies. The total write-verify cycle count is shown on a display — watch a live video feed and guess when the first chip will die. This project was inspired by the inevitable comments about flash longevity on every Slashdot SSD story. Design files and source are available at Google Code."
Mechanical disks have lots of great failure modes. You can do seek tests until the arm breaks or voice coil fails, you can do write/read tests until you get enough bad sectors that they can't recover the data any more, or you can do start-stop of the drive motor until it dies. Another good one is to stop the motor for a while, then see if it starts up or has stiction (sic), but that test takes a long time. If the drive is not held rigidly enough, vibration will kill it, and it it isn't cooled properly, heat will kill it. Did I miss any?
Most modern flash memories have their controllers check which blocks are dying or dead and re-route write and read requests to good blocks. So while your flash may seem to be working perfectly well, various blocks inside it may be dying and its storage size may be progressively decreasing.
So I hope they are rewriting the entire flash in their test. Otherwise it is not representative.
Assuming that the flash is of equivalent technology (e.g. SLC NAND, cell size, etc) to that used for SSD, then this would present a best case test, since it is exercising all cells equally.
An SSD tries to do wear leveling (distribute writes evenly), but that can't done perfectly, as is done in this test.
"National Security is the chief cause of national insecurity." - Celine's First Law
And honestly it's a pretty valid argument. This is definitely going to be informative, but I'm just as interested in how a particular SSD handles the flash blocks failing as when they fail. A SSD with flash that averages 1,000,000 writes before blocks start to fail but does it gracefully with little/no data loss could be better than one that averages 2,000,000 but goes out in a blaze of glory as soon as the first block fails.
"Always forgive your enemies; nothing annoys them so much." - Oscar Wilde
Or connect the drive inside any computer running a Prescott P4 with 100% CPU utilization.
Tequila: It's not just for breakfast anymore!
Graceful as in data not related to your recent failed writes are still readable so they can be backed up and migrated to a new drive. Not sure why that concept is so difficult. I consider something dead as "completely unreadable, ALL your data has been destroyed - have a nice day."
No longer reliable but still semi recoverable isn't quite "dead."
Maybe I'm just using a stricter interpretation of the word dead than you are?
Let's use a marker on a white board analogy. If I was storing all my data on a suitably large white board using a marker and I completely exhausted my marker's supply of ink, I'd be pissed if this resulted in a blank whiteboard, wouldn't you? On that same note, if I wiped a small section of my whiteboard with the intent of writing something new in that area and only then realized that my marker was no longer suitably supplied with ink and my write failed, I would find the blank void in that section alone acceptable.
Does that clarify things?
I just hang around on the NCIX forums, and every day or two there's a person complaining about having to RMA their SSD because programs started crashing, and then finally they couldn't even boot it.
I saw lots of people replying in threads, saying theirs were still working fine. I started asking everyone how long they had owned theirs. Most with working SSDs were in the 8-15 months range, and most with serious problems were in the 12-24 months range.
I've noticed that SSD warranties from a lot of manufacturers have dropped from the original 5 years down to ~2. That's quite a drop. There must be a reason.
I suspect a heavy disk user like myself would burn through one well before the warranty is up.
Note: My sample is pretty small compared to the amount sold, but I do wonder how many die without the owners being vocal about it.
I'm wondering if close to two years ago manufacturers flipped to cheaper NAND to get the prices down? Now prices are going back up, so maybe manufacturers realized their mistake? Even since January, SSD prices have gone up 20-30% on average. $89.99 SSDs are now $120+
http://www.newegg.com/Product/Product.aspx?item=N82E16820167025&Local=y