On Tue, 2022-12-27 at 13:47 +0000, Tim Woodall wrote: > On Tue, 27 Dec 2022, Tixy wrote: > > > On Mon, 2022-12-26 at 21:37 +0000, Tim Woodall wrote: > > > > > > > But now I'm concerned about disks in a raid-1. Everything gets written > > > when the raid rebuilds. > > > > > > I've found fstrim - but that only seems to be for filesystems. > > > > > > How do I tell the card that the free space in the VG really is free? > > > > You probably can't. I've not heard of removable cards supporting the > > 'trim' command. > > > > > I found a issue_discards setting in lvm.conf. Set that, then created a > LV using the remaining space and deleted it again. > (this wasn't an sd card, was my main machine that I run in a raid-1 > configuration) > > There's definitely something implemented on sd cards: fstrim works on an > identical, working, card while it fails on my broken one.
Interesting, doing a Google search finds that SD cards do support this... https://superuser.com/a/1554860 Though that was with an actual MMC device though, don't know about the interfaces which now all seem to be implemented at the end of USB. In fact the forum reply above says: USB to SD card adapters ("SD card readers") could support this command by advertising the TRIM or UNMAP commands via the USB storage interface, and translating these to the MMC_ERASE command, but I've yet to find a USB adapter which does this. -- Tixy
