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Log-structured file systems: There's one in every SSDLog-structured file systems: There's one in every SSDPosted Oct 2, 2009 17:58 UTC (Fri) by djcapelis (subscriber, #53964)Parent article: Log-structured file systems: There's one in every SSD
IIRC some of the next generation SSDs based on phase-change memory and some other things don't require any of this madness.
Samsung is doing phase-change memory at scale now. The capacity is smaller than we'd like, but it's actually here and in production finally.
(To be fair write cycles on PCM aren't infinite, but at 100mil cycles and writes on the bit level instead of the block level, PCM is a good deal that likely to make SSDs less annoying in the future. PCM isn't the only type of new SSD that's coming out with this stuff.)
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Log-structured file systems: There's one in every SSD Posted Oct 5, 2009 20:48 UTC (Mon) by joern (subscriber, #22392) [Link]
When talking to hardware people who want to market PCM, you may notice that it suffers a similar problem as flash SSDs do. Since there is no PCM software stack, they want to plug into an existing software stack by pretending to be something else. And from what I've heard so far, that something else will be NOR flash.
Which isn't too bad an idea, honestly. 100M may seem big, but if you are ignorant enough and write your filesystem superblock on every sync, you can have that worn out in just 24h. So you still need some amount of wear leveling.
Plus, the programming of PCM is asynchronous. Flipping a bit one direction is about 6x slower than flipping it the other way. Which means that by treating your random-writeable PCM as block-eraseable flash you gain a speedup that can more than counter the slowdowns from garbage collection under fairly realistic conditions.
Log-structured file systems: There's one in every SSD Posted Oct 7, 2009 7:17 UTC (Wed) by mcortese (guest, #52099) [Link] Plus, the programming of PCM is asynchronous.I guess you meant asymmetric?
Log-structured file systems: There's one in every SSD Posted Oct 7, 2009 11:27 UTC (Wed) by joern (subscriber, #22392) [Link]
Of course I did. Thanks.
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