The bulk storage device will store the majority of our data. The data will be non-critical, so the device does not need to be as reliable as our safeguard memory.
The stored data will consist of telemetry (diagnostics, events, stats, etc.) and payload (compressed images) data separated into folders.
Description
NAND flash is a non-volatile type of computer memory that can be erased and reprogrammed. It's typically used for file storage (In contrast, NOR flash is typically used for code execution) and it has a high storage capacity. Because of the particular characteristics of flash memory, it is best used with either a controller to perform wear-levelling and error correction or specifically designed flash file systems, which spread writes over the media.
In practice, flash file systems are used only for memory technology devices (MTDs), which are embedded flash memories that do not have a controller. Removable flash memory cards, SSDs, eMMC chips and USB flash drives have a built-in controller so the use of a specific flash file system does not add any benefit.
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Description
microSD (Secure Digital) cards contain a tiny microcontroller and NAND flash. The microcontroller implements an FTL (Flash Translation Layer) that takes disk-like block accesses and translates them into meaningful NAND operations, as well as performing wear-levelling and block sparing. SD cards use the SPI protocol on the "host" side.
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