Everybody is good:
SLC NAND using UBIFS file system, a BLOCK NAND to 128 KB (PAGE=2 KB), assuming that there are many small files (every 10 k), if every small files take up at least one BLOCK (128 k) space, if so NAND space utilization is too low?

Thank you very much!

CodePudding user response:

Certainly can't, so it is better to read nand got directly, is divided into system format partitions have what use?

CodePudding user response:

UBI work directly on the Flash, in brief, in UBI's view, Flash is by numerous or good or bad can erase blocks, each can erase block can read, write, can erase, good can erase block may become bad,

Read and write Flash unit is the smallest, speaking, reading and writing, it depends on the type of Flash,

* the smallest read/write of NOR flash unit is mostly 1 byte, this is because most of NOR flash can read and write in single-byte,

The smallest, speaking, reading and writing of some NOR Flash unit may be 16 or 32 bytes, because to deal with ECC,

* NAND Flash unit is 1 page, the smallest, speaking, reading and writing data in NAND Flash page updated, must write a full page to a new page, because the page does not support NAND Flash write repeat, and must be written from page to page in sequence, a new page could be written to other blocks with empty pages,

CodePudding user response:

@ jklinux
Based on Linux system, it is impossible to directly manipulate NAND
@ of123
Although NAND erase the smallest block (128 k), but the least read, write unit is indeed a page (2 k),

CodePudding user response:

Block is erased, is write small file, a page

Different FLASH page size are different, so according to the actual production system to optimize write

That is to say: SSD firmware, within their own management, if you one-time write file is greater than or equal to a block, it will be directly in the table to find the corresponding new blocks to write directly, but if you write the file less than a page (or even less than), it will be in the available position in the table to find the corresponding position, continue to programming in directly, not to erase the whole block (page is the smallest unit of reading and writing, block is the smallest unit of erasure)

FLASH is a few movements, one is read, a programming is action, one is the erasure action (only one block have multiple pages by GC, the firmware mechanism will carry, and then erased, erased to tell the information I can use the corresponding form, as to the service life of block is erased, so some not so positive, the mechanism of the firmware will result in performance degradation or other)

CodePudding user response:

The Page write Nand is followed, erasure is according to the block

CodePudding user response:

If there is no but bit operation, block is the smallest unit

CodePudding user response:

Nandflash is used to store large files,