Log-structured file systems: There's one in every SSD

Posted Sep 22, 2009 11:08 UTC (Tue) by nye (subscriber, #51576)
In reply to: Log-structured file systems: There's one in every SSD by ikm
Parent article: Log-structured file systems: There's one in every SSD

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.

But thanks to both for making it explicit.

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Log-structured file systems: There's one in every SSD

Posted Oct 6, 2009 16:45 UTC (Tue) by sethml (guest, #8471) [Link] (1 responses)

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.