4 Matching Annotations
  1. Oct 2018
  2. Jul 2018
    1. Use eMMC in Data Reliability Mode Typical eMMC devices also should not be powered down during a write/erase cycle, as they can be prone to the same failures as an SD Card. However, the eMMC devices that Technologic Systems uses in our products include support for a "Write Reliability" mode, and a "psuedo SLC" mode. These modes can be access by setting a fuse on the eMMC device. With both of these enabled the eMMC only risks up to 512B during a write. In the event of a power loss that 512B of data would return the values from a previous write rather than corrupt or erased data like a typical SD card. Even in cases where the wrong data is present on the next boot, fsck is able to deal with the older data being present in a 512B block. The downsides to setting these modes are that it will about half the size of the eMMC module to 1.759Gib by default, and write speed will be slightly slower. Used with ext3/4 and the filesystem configured to journal data, this can provide a very robust system. This mode still has the tradeoff that any data not yet committed to disk will be lost.

      使用 eMMC 的数据可靠模式(可靠写入模式 + 伪 SLC 模式)可提高存储设备的断电耐受能力。