On Thu, 14 May 2020 at 18:04, Lennart Sorensen via talk <talk@gtalug.org> wrote:>
On Thu, May 14, 2020 at 05:20:18PM -0400, D. Hugh Redelmeier via talk wrote:
If your filesystem lives on some form of flash (SSD, SD card, USB stick, ...) this can reduce the lifetime and performance of your hardware.
The wear-levelling firmware of the drive will think that every block of the drive is "live" (contains valuable information). This will increase "write amplification".
In any case, if you do do this, be sure to use fstrim afterwards. (I'm not sure that SD cards and USB sticks support trim.
I think the idea was to do it on the image loop back mounted, not on the original device.
What all this discussion has made me realize is that I have to either A) modify the original SD card or B) loop mount and modify the backup. Option A was what I was initially proposing, but forcing a write (zeroing out most of the contents) across the whole card isn't a great idea. Not terrible, but not great. Option B involves modifying the backup, and I think this is a worse idea because 1) a backup should be an accurate recreation of the source, and 2) modifying the backup effectively means you'd be restoring something different, and do I really feel comfortable counting on that? The more I think about it, the less I want to modify either of them. Thanks for clarifying the process: it solidified my opinion on what should be done (although not in the direction I expected). ie. 10G really ain't that big, I'll just keep the backup as is. Thanks everyone. -- Giles https://www.gilesorr.com/ gilesorr@gmail.com