This is indeed obvious now that I'm awake (somewhat embarrassingly so :P).
I think the bit that I was somehow missing was that 'reading' from an unmapped block should just return all zeroes.
Log-structured file systems: There's one in every SSD
Posted Oct 6, 2009 16:45 UTC (Tue) by sethml (subscriber, #8471)
[Link]
The problem with this approach is that transferring zillions of zeros over the disk interface is
slow. Imagine if deleting a 10gb file took several minutes - that would be rather annoying.
Too bad SATA doesn't have a "write a million zeros" command. Of course, that's effectively
what a proper TRIM would do.
Log-structured file systems: There's one in every SSD
Posted Oct 6, 2009 19:59 UTC (Tue) by ikm (subscriber, #493)
[Link]
True. But it still might be better than the current TRIM implementation -- if not performance-wise, then at least compatibility-wise. The blocks could be zeroed in background when the I/O is otherwise idle.