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The 2.6.29 kernel is outThe 2.6.29 kernel is outPosted Mar 24, 2009 11:34 UTC (Tue) by ssam (subscriber, #46587)Parent article: The 2.6.29 kernel is out
Great to see the 'Ext4 no journal mode'.
I guess this is to guarantee data loss after hard crashes and power outages. POSIX FTW
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The 2.6.29 kernel is out Posted Mar 24, 2009 11:40 UTC (Tue) by kragil (guest, #34373) [Link]
The patch is from Google (they still use EXT2) because they just reimage a machine when it crashes.
Sometimes you don't need a journal but you want the added speed and features.
The 2.6.29 kernel is out Posted Mar 24, 2009 12:21 UTC (Tue) by epa (subscriber, #39769) [Link]
Yes, obviously if your application requires the data to be stored permanently it should call fsync()!
The 2.6.29 kernel is out Posted Mar 24, 2009 13:04 UTC (Tue) by clugstj (subscriber, #4020) [Link]
Let's not start this again!
The 2.6.29 kernel is out Posted Mar 25, 2009 6:42 UTC (Wed) by bojan (subscriber, #14302) [Link]
But it was so much fun! ;-)
The 2.6.29 kernel is out Posted Mar 24, 2009 20:46 UTC (Tue) by muwlgr (guest, #35359) [Link]
Google do not use fsync. They use triple redundancy for their data and handle single storage node faults as usual in-process working events (i.e. bring the redundancy back to 3, and replace the failed node with a new empty operational one).
The 2.6.29 kernel is out Posted Mar 24, 2009 15:45 UTC (Tue) by nix (subscriber, #2304) [Link]
Journals only protect metadata, not data. Google don't care how long fsck takes (they never run it), but they *do* care about I/O rates. So they don't want to use a journal.
The 2.6.29 kernel is out Posted Mar 24, 2009 18:19 UTC (Tue) by tialaramex (subscriber, #21167) [Link]
The data=journal mode protected data, didn't it?
But yes, some people (and Google are apparently enough people to count) want the best possible FS features minus journalling.
Also fsck is probably /faster/ in ext4 than ext2, so Google would be wise to choose ext4 w/o journalling over ext2 even if they did care about fsck performance. Sparse inode structures iirc were a particularly big fsck win.
The 2.6.29 kernel is out Posted Mar 24, 2009 19:59 UTC (Tue) by cortana (subscriber, #24596) [Link]
Apparantly not. I think you want the 'sync' mount option in this case.
The 2.6.29 kernel is out Posted Mar 24, 2009 20:45 UTC (Tue) by tialaramex (subscriber, #21167) [Link]
Ted's talking about ext4 there, not ext3. Combining delayed allocation with data journalling clearly doesn't make much sense. But point taken.
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