1. The P/E cycle of some MLC NAND flash blocks tested exceeded the 3,000 cycle specification in datasheets, with some blocks reaching 20,000 cycles. 2. Each block has independent characteristics that affect lifespan, so blocks from the same production process will have varying lifetimes. 3. Testing is needed to characterize NAND flash from different sources and sort them by quality levels since initial conditions vary between blocks. 4. Understanding how error rates change with P/E cycling can help optimize error correction coding over the lifespan.

1. Is the P/E cycle of MLC really only 3,000 times as its datasheet said?
Firstly, let’s see the conclusion that Renice draw based on the test from Nand Flash test platform
NFA100.
1, the P/E cycle of some Block up to 20,000 times in real test, though it said only 3,000 times in
datasheet.
2, Each block is an independent individual, and the initial condition of each block is not exactly
the same, even though they are the same process in the same production line.
3, No matter it’s original Nand Flash or non-original, they have the necessity of testing, the Nand
Flash can be sorted and classified into different levels.
4, Though it is the same Nand Flash chip, the health condition of each Block is not the same
5, The real lifetime (P/E cycle) of Nand Flash may be far greater than its datasheet, only when test,
it can play the greater value.
6, Deep understanding of the life performance of Nand Flash in different P/E stages can help
better plan ECC.
7, For those who want to convert MLC mode to SLC at a certain stage, when to start conversion is
crucial, its RBER corresponding to P/E is the most important reference.
Here is the correlation of P/E and RBER,
Enlarger

2. The test took 108h and 45 minutes.

3. Renice test process:
Test 16 Blocks, make each Block initialize pseudo-random
variable. Each Block and each Page use different
pseudo-random number
Erase Block (Block 3, 1051, 2091, 3103, 2, 6, 1050, 4055, 1049,
1053, 2089, 2093…)
Program Block, initialize pattern by Step1
Initializing seed +1
Erase Block (Block 3, 1051, 2091, 3103, 2, 6, 1050, 4055, 1049,
1053, 2089, 2093…totally 16 Blocks)
Program Block, initialize pattern by Step1
Record Error Bit every 20 P/E times
Pseudo-random seed +1
1,000 rounds, totally 20*1000=20,000 times
Totally20P/Etimes
Repeat
19 times
1st
time
1, The selected Block has a discrete distribution and adjacent distribution (2, 3, 1050, 1051)
2, Each Block and the Page of the Block are Pseudo-random number.
3, The next P/E will automatically +1 to the last pseudo-random number to ensure that the
pseudo-random number written this time is completely different from the last time.
4, Record the number of bit Errors every 20 P/E times.
5, The interval between Erase and Program is 0
6, 22,960 times of P/E corresponding bit Errors (20*1148=22960) data record took 108 hours
and 45 minutes.
7, Renice use Intel MLC Nand Flash (3,000 P/E cycles) for testing.
8, Worksheets are named in decimal, e.g., Block3130 represents Block 3103 (0C1F)