On Sun, 6 Jan 2019 10:23:19 -0000 (UTC), Markus Robert Kessler
 declaimed the following:

>- Is Kingston known as having severe quality problems?
>
 Kingston does not manufacture SD cards -- they buy up blank units from
lowest bidder makers and put their label on them. I believe PNY is similar.

 Don't recall if Transcend is a maker or relabeler, but have a small
feeling that if they do relabeling, they may still be using higher quality
cards.

>- Is there anything I could do to try find out, what exactly went wrong?
>

 SanDisk (and Lexar to my knowledge) have their own silicon foundries,
and would be a recommended choice. I did have a Kingston card for my first
RPi -- and managed to kill it when running a benchmark suite (it did not
survive having a section allocated to a swap file -- eventually had to run
the benchmark with a TB USB drive for swap).

 Note that SD cards are natively formatted in FAT -- a NON-JOURNALING
file system. Linux EXT# (and NTFS) are journaling systems. Journaling
systems are supposed to reduce the effects of corruption as they keep a
journal of changes being made, and at later/idle periods finalize the
changes. Power-failure in mid-update means either the update is completely
lost (no change to original file), the journal is lost (so all updated data
is lost, but no changes to original file), the journal and update were not
lost, and can be used to finalize the actual file... But journals are "bad"
for flash memory due to the amount of activity performed.

 Also, cheaper memory cards may only maintain two "open allocation
units" (one data file, one file allocation table), and a journaling system
can easily be using three or more open AUs (data file, journal, and
equivalent of FAT). On a two AU card, changing from AU to AU means flushing
updates to an AU, locating a free AU in the card, ERASING that AU (SD cards
can only write once to a sector without erasing), COPYING static parts of
an old AU to the newly erased one, then appending new/modified data to the
AU.

 Note that lower quality class 10 cards may perform very badly with file
systems that are not streaming data. Class 10 cards are rated for writing a
video stream to a freshly formatted card (so 2 AUs are all that is needed).
Class 2/4/6 cards, OTOH, are rated for writing small (photos, for example)
files to a fragmented card (reflecting someone who has deleted some photos
between shoots) -- they can often beat the performance of a cheap class 10
when lots of small files are being accessed.

CF:
https://wiki.linaro.org/WorkingGroups/KernelArchived/Projects/FlashCardSurvey?a
ction=show&redirect=WorkingGroups%2FKernel%2FProjects%2FFlashCardSurvey
(a bit old now, but the concepts are the same -- look at the # open AUs
columns; in a quick glance, Kingston manages just 1 AU, SanDisk 3-6, and
Transcend 5)

Also: https://lwn.net/Articles/428584/


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