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SD card duration - Armin@netPI - October-27th-2017

Watch your Docker applications how stressful they are to the memory card. Critical are those writing data at high volumes in the long term.

netPI includes an 8GB micro SD card of type MLC-NAND from seller company Xmore with part number SDU008GXASMM-001E. The most critical thing about a NAND flash memory is its finite number of erase/program cycles (P/E cycles) also referred to as "memory wear". The wear begins to deteriorate the integrity of the memory until it is becoming unusable in the end.

netPI's industrial grade card has a limit of 3000 P/E cycles per flash block specified by its manufacturer Toshiba. The limit per block makes a NAND-flash endurance directly dependent on its size, so the bigger the better. An auto-wear leveling mechanism in the card ensures the next erase/program cycle is performed on another flash block and hence distributes them evenly across the medium.

10 years life time in theory: There is a lifetime calculator available from Toshiba estimating the expected NAND flash life time. With netPI's 8GB @ 3000 P/E cycles it outputs a ratio of 1650 MB/day you may write to the SD card to guarantee a 10 years life. In total this is 1650MB x 365days x 10years = 6022500MB or 6022GB or 6 TB of data the SD card tolerates.

30 years Life time in practice: We made tough tests with an SD card to check its endurance under real life conditions. We brought a card to its limits at a incredible rate of 450000MB/day and realized the first failure after writing 18TB of data. So in reality an SD card has a 3 times higher endurance compared to the very conservative value the calculator provides.

... so keep an eye on your applications.

Answer - Armin@netPI - May-18th-2018

If the endurance of netPI's standard 8GB micro SD card is not sufficient for a use case then of course we support OEMs with netPIs populated with different type of SD cards of type pSLC or SLC.

Just to give you a slight impression about pricing for an equivalent 8GB high endurance mirco SD card of type SLC you can follow this link to distributor Mouser at https://www2.mouser.com/ProductDetail/Swissbit/SFSD8192N1BM1MT-I-QG-221-STD?qs=sGAEpiMZZMtyMAXUUxCBE1dP411q9FJNKuP2Jc1o5NJlMgKL%252b%2fCokg%3d%3d
showing you an industrial suited SFSD8192N1BM1MT-I-QG-221-STD from Swissbit at a price of $128 (instead of $10 a MLC card would cost typically)