On Fri, Oct 29, 2010 at 01:17:23PM -0700, Leslie S Satenstein wrote:
> In a few earlier postings I indicated the problems I had with EXT4 and a hard 
> drive that was about 75% full (320gig at 75%). Performance was such that 
> simple uploads or downloads crawled to a 10k / second pace, or even stalled 
> for long periods of time.

I use ext3, and have not had this problem.  But then, I don't have any nearly 
full USB drives to have the problem on 
either.

> 
> I read an article about btfrs and how it is designed as copy on write. That 
> is, write the new data, then change the B tree to point to the new sub-tree 
> of data.

I thought that was the pronciple behind the reiser file system.  I also heard 
that the reiser file system was hell to 
repair if something *did* manage to go wrong.  I'm not sure of the details, but 
I hope btrfs is better.

-- hendrik

> 
> Ergo, if someone inadvertantly pulls out the drive's plug from the USB 
> physical port, we are almost guaranteed to not have drive corruption. There 
> may be some data loss, but no drive corruption.  That to me is most important.

There might be physically part-written blocks if the drive relies on power 
that's suddenly gone.  I'm not sure how 
part-written blocks work ont when the time comes to rewrite them ...  I gather 
it's the kind of thing hardware-level 
disk-checkers look for.

> 
> I am not certain about storage efficiencies.  Would 10gigs of data with EXT4 
> use less diskspace than 10 gigs of data stored in btfrs format.  (What's a 
> gig when terrabyte drives sell for around $60.00.

No idea.  But if I recall correctly, when I changed from an ext2 file system to 
a reiser file system total available 
storage went down slightly.  It wasn't a big deal.

-- hendrik
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