In general only writes cause wear but the card might be doing some in the background - most cards do internal housekeeping and will detect and remap weak sectors without you even knowing, so it's very hard to tell.

I think that unless you are doing a lot of writes to that card, and that include not only user apps but also things like swap files, there is no point in worrying about that. If you were to not use the card at all then flash cells (especially the modern, dense / multi-level ones) will slowly loose charge and glitch the data after a decade or two. Some modern SSDs can only last about 6 months when unpowered. Granted, that is not card damage since it can be just re-written but it is data loss.

Hi. This site has some information about the topic:

https://pcengines.ch/cfwear.htm

It's not up to date anymore, sadly.
When it was written, there was SLC and MLC only.

KingThistle wrote on 2023-01-03, 23:38:

I know that TRIM and what not isn’t supported on older OSs but what’s that going to do real world

Nothing because most memory cards of all major kinds don't support it in the first place, knowing that most (all?) cameras and $5 USB readers won't use it even if they knew 😀

They also tend to last relatively little and have unremarkable performance because the non-industrial types are usually optimized for sequential writes (photo and video recording): that's as true in a 286 as it is on a Pi (which should support the SD block erase command...)!

https://web.archive.org/web/20101121233926/ht … e-enhancements/

Key Feature Enhancements
Ultra DMA Mode 7 Provides an interface speed of 167MB/s. This speed enhancement enables a new generation of higher performance cards while providing complete backward compatibility.
Sanitize Command Provides an efficient NAND Block Erase of the entire user data area to return the CF card to “fresh” state before reuse or repurposing. Leverages a command defined in INCITS T13 ACS-2.
Trim Usage Guidelines Provides improved write performance consistency.

Anyone ever verify that they got TRIM to work on their CF?
Anyone ever see UDMA Mode 7 on a PC?

Pc stopped at UDMA 133 due to SATA 2/3 being faster by that point.

douglar wrote on 2023-01-04, 21:39:

Anyone ever verify that they got TRIM to work on their CF?
Anyone ever see UDMA Mode 7 on a PC?

TRIM is a part of ATA commands and can be initiated in DOS (Rudolph R. Loew utility).
UDMA Mode 7 can be replicated by SATAII in compatible mode. Why would you need to use slow as fungus CF card on SATAII capable platform is another question.