[sf-lug] filesystem for a 3TB external USB drive

Ian Sidle ian at iansidle.com
Tue Jan 3 21:12:09 PST 2012

> I don't know why EXT2 has even been mentioned as a possibility.

IMHO, ext2 isn't significantly different than ext3, besides it having a journal duck-taped to the side of it (which then slows it down quite a bit).  You can take an EXT3 formatted volume, mount it on a system that is only capable of reading EXT2 and it will run just fine. True. the journaling feature does /not/ work in that situation, but you can't expect it to do something it wasn't programmed to do. 

Also, even though fsck can take a considerable amount of time, it is still the "for sure" way to check for filesystem consistancy. Journaling provides a shortcut to speedup the process, but some filesystems (like ext3) will force you to do a full fsck scan every once in a while because they assume stuff will slip through the cracks.  

FYI - You *can* adjust that parameter, to make it more frequently or less frequently then the recommended values and I think even turn it off entirely if one is so trusting.

EXT4, on the otherhand is (from my understanding) a significantly different animal then ext2/ext3 is. True, you can "upgrade"  from ext3 to ext4, but that process is not reversible and you loose compatibility with OS's (i.e. windows) that only understand ext2. 

From what I've seen, you can do a "dirty mount" and use an ext2 driver to load an ext4 disk, but it seems YMMV with how well it will work and your stuck with it being readonly. 


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