snottmonster;628706 Wrote: 
> This just made me realise that I actually have 4 more ext4 drives as I
> use them for additional backups. They are installed in USB 'caddies'
> 
> I remember measuring the performance some time ago and was regularly
> getting 20-25MB/s writes and upto 30MB/s reads which in both my testing
> and reading is about the *practical* limit of USB2 in a typical PC setup
> - so certainly no slow down.
> 
> That said, I'm really unsure of what to suggest re. the experience
> @gharris999 is getting. I'll take a look at them when I can disconnect
> and see if there's anything particular about the setup
> 
> One thought that does come to mind - I've seen reports on other forums
> that in improperly aligned filesystem on a 4K sector disk typically
> shows itself via a slowdown in access. Unfortunately I don't (yet) have
> such a disk as mentioned previously to test this out, but might be
> something to look more closely at?
>From what I've been reading, the last several linux kernels
automatically take care of the 4k alignment problem.  But I have to
admit that this topic is a little over my head.  I more or less blindly
trusted that gparted on a fully up to date Fedora 14 would correctly
account for this and create a GPT and ext4 fs with the correct
alignment.  

Certainly, while not specifically timing this, my script file which
performed several rsyncs to push about 1.5TBs of data onto the new disc
seemed speedy enough...maybe even faster than the equivalent robocopy
routines that I use on the windows side to push the same data onto ntfs
formatted drives.  So write performance to this ext4 Hitachi drive
really isn't in question.

Again, my only quandary here is why full SBS wipecache scanning is so
markedly slower on this system using ext/2/3/4 than when using ntfs-3g.
This is what flies in the face of my expectations.

I should mention that the ntfs-3g fs driver in linux saw a marked
performance improvement within the last several months.  My ntfs-3g
scan times dropped from about 45 minutes to 26 minutes sometime in
March.  

I was primarily motivated to switch to ext2/3/4 because of a
fragmentation problem I was having with the ntfs drive.  I was finding
that SBS would occasionally fail to complete a scan and the whole
system would freeze.  Removing the audio drive to a windows machine and
defragging it would solve the problem for a month or two.  Juggling this
drive was kind of a pain so I thought that switching to ext2/3/4 would
solve this problem.  We'll see...I expect that is has.  But I didn't
expect to pay a performance penalty in the process.


-- 
gharris999
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