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Ext4 filesystem hits Android, no need to fear data loss (ars technica)Ext4 filesystem hits Android, no need to fear data loss (ars technica)Posted Dec 28, 2010 17:34 UTC (Tue) by mikov (subscriber, #33179)In reply to: Ext4 filesystem hits Android, no need to fear data loss (ars technica) by Los__D Parent article: Ext4 filesystem hits Android, no need to fear data loss (ars technica)
Of course there lots of inefficiency in an independent controller. Before all wear leveling needs free space - without understanding the file system layout, and without the trim command, the so called "hardware" wear leveling (it is misnomer, of course) is very inefficient. AFAIK, the trim command itself is problematic because it is synchronous.
I have had horrible experiences with CompactFlash cards, even expensive ones from respected vendors.
I think few people realize how truly difficult it is to do good wear leveling. Even reads cause wear! Plus, the obvious "solutions" have a write multiplication factor of about 30...
This problem has been largely ignored recently to the extent that it isn't even mentioned at all in supposedly technical articles.
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Ext4 filesystem hits Android, no need to fear data loss (ars technica) Posted Dec 29, 2010 4:15 UTC (Wed) by jzbiciak (✭ supporter ✭, #5246) [Link] I think few people realize how truly difficult it is to do good wear leveling. Even reads cause wear! Really? I've never never heard that reads cause any appreciable wear. Can you share a reference?
Ext4 filesystem hits Android, no need to fear data loss (ars technica) Posted Dec 29, 2010 15:14 UTC (Wed) by busterb (subscriber, #560) [Link]
Just use the 'noatime' mount option.
Ext4 filesystem hits Android, no need to fear data loss (ars technica) Posted Dec 29, 2010 20:16 UTC (Wed) by jzbiciak (✭ supporter ✭, #5246) [Link] atime updates are writes (even though the app only does a read). The comment I was replying to seemed to suggest that pure reads wear out flash. ie. if I mounted a volume read-only, that I could shorten its life dramatically by reading it regularly. While I'm sure there's some impact to reading a flash cell, I've got to believe it's a few orders of magnitude smaller than the effect due to writes, and therefore generally ignorable.
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