[Swlug] Mysterious errors

[Neil Greenwood]

On Tue, 9 Jan 2024, 15:58 Rhys Sage via Swlug, <swlug at mailman.lug.org.uk>
wrote:

> Now I get a result. Thanks Neil. I'm not sure where that gets me as to
> "drive" health though.
>

"eMMC on its own does not track write cycles like standard drives and does
not have mechanism like smart. You can use mmc extcsd read /dev/mmcblk0
from package mmc-utils to take a peak in to amount of used reserved blocks.
That is field EXT_CSD_DEVICE_LIFE_TIME_EST. Value is in range of percents
so 0x01 is from 0%-10% blocks used, 0x02 is from 10%-20% and so on. When
amount of reserved block used is close to 100% then NAND is pretty much EOL.

You should know that this is not linear. This is secondary statistics and
tells you nothing about complete wear. Common wear is an avalanche effect.
Nothing is happening for a long time and then all blocks starts failing at
once. Meaning percentage of used reserved blocks might start rising very
quickly."

>From https://forum.turris.cz/t/emmc-live-span-health-monitoring/9958/9

Hopefully this helps. I've never owned an MMC device to my knowledge...
Although my Chromebook might have one.


Neil

>
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