New-Tech Europe | September 2016 | Digital Edition

on the media and not written to again) and compared that to a situation with approximately 60% static data. The variance between the highest and lowest values for each test case are shown in this table.

100,000 erase cycles.

Simulation Tests For purpose of testing the effectiveness of wear-leveling amongst various flash management software, we used the following test: 1. 64MB of NAND Flash configured in small and large block configurations. a. Small Block - 16KB (4096 blocks) b. Large Block - 128 KB (512 blocks) *Large and small block NAND were two different hardware configurations available at the time we performed this test. The results show that the variance of wear-leveling can be greater on large block, because the wear-leveling of static data happens less often. 2. Fill part of the volume with a large file that is not modified. This represents the static data on disk. For the first series of tests, we used 10% static data. 3. Fill remaining portion with another file that is constantly modified. This represents dynamic data a. Copy data in the file b. Delete data c. Repeat above steps for 10,000 cycles 4. Measure the variance in the number of erase counts for blocks on the disk. The smaller the variance, the more effective the wear-leveling technique used FlashFX Family vs. JFFS2 Results We measure the effectiveness of wear-leveling algorithms by examining the erase count for each block on the media, then comparing the highest value to the lowest value. We measured this in a situation where approximately 10% of the data on the media was static (placed

These graphs show the erase count all 512 flash media blocks, over a range of 4000 erase counts. JFFS2 has erase counts which vary greatly within this range, while FlashFX Tera keeps the erase count within a range of roughly 900 erases.

These graphs show the erase count all 4096 flash media blocks, over a range of 8000 erase counts. JFFS2 has slightly better wear-leveling than on large blocks, keeping the erase count within 2500 erases, but FlashFX Tera keeps the erases on a narrow band of roughly 900 erases.

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