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Root ext2 vs. ext3 vs. ext4. What is better and why?

Discussion in 'Android Devices' started by Matt's 175, Jan 15, 2011.

  1. Matt's 175

    Matt's 175 Well-Known Member
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    Can someone explain this to me a little bit? What's better?
     

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  2. savoxis

    savoxis Android Expert
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  3. Viper05

    Viper05 Well-Known Member
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    Personally I was a bit curious on this as well. Would anyone care to make suggestions as it pertains to our phones and a Micro SD card? From what little I know of Linux, EXT4 is preferred for performance compared to EXT2 or EXT3, and EXT3 is better than EXT2. But I'm unsure if it is any different on our phones.
     
  4. morchus

    morchus Lurker
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    journaling is the main advantage of ext3 over ext2. But the same journaling can be bad for the life of an flash or an sd-card (because you do more writes). If you are not worried about life of the card, and the choice is based on filesystem performance only then ext4>ext3>ext2. By the way, ext4 can be used with journalling switched off, but then you loose the performance advantages.

    Now another thing to worry about is recovery (from data corruption). There again ext2 is worse than ext3 and ext4, again because of the journaling. In summary, journaling is bad for life of sdcard/flash, but you get all the advantages of ext4/ext3 from journaling.


    morchu
     
  5. donallen

    donallen Lurker
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    "By the way, ext4 can be used with journalling switched off, but then you loose the performance advantages." This is incorrect. The journal actually slows the filesystem down, because extra writes are being done to the medium. So performance is going to be somewhat better with the journal turned off. The price you pay for that is the need to do a full file-system check (fsck) after an abnormal shutdown. This can take a long time on a big file-system and there's a small probability of not being able to recover the file-system (I've run ext2, which takes the same risk as ext4 without a journal, for many years on many machines. I have never seen this in practice.).

    Personally, I continue to use ext2 on most of my machines, because of its performance advantage over ext3. I'm not worried about having to endure long fscks, because they almost never happen. I always shut my systems down correctly, and Linux crashes exceedingly rarely. I'm in the process of migrating to ext4 with journaling, because it does offer some performance advantages over ext2. Google has done the same thing for the same reasons.

    /Don Allen
     
  6. Zoe Moyo

    Zoe Moyo Lurker
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    A few of you lads here mention that therer are alot of performance advantages of using EXT4. I am wondering what they are exactly?

    Best

    Zoe
     
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