Different filesystems

Frank Carmickle frankiec at braille.uwo.ca
Sun Nov 11 15:45:54 EST 2001

On Sun, 11 Nov 2001, Kirk Wood wrote:
> > ext3.  There was a 2gb limit for ext2 at one point.  
> Umm, while I can understand that someone somewhere may find 2GB a limiting
> factor for a file, why would *I* worry about this limit? If I have a
> single firle that big, I have other things to worry about.

Like what?  There are lots of times when you have greater then 2gb files.  
Consider the case of digital audio or digital video.  It doesn't take to
long to reach this limit.  Let's do a little math on pre ac3 or dts
encoded surround.  I've got 6 channels of 24 bit 96khz audio.  Let's say
that this is the sound track for a movie that is 2 hours in length.  
Almost all of the audio cards that support 24 bit 96k actually read and
write 32 bits.  For my math I'll use 4 bytes.

(((((((4*96000)*60)*120)*6)/1024)/1024)/1024) = 15.44952392578125 

So we have ourselves a nice 15.5gb file.  Let's hope that we can put that
on our filesystem.  Let's do some other math while were at it.  How fast
do our disk or disks need to be to make this play with out drop outs?

((((4*96000)*6)/1024)/1024) = 2.197265625

With 2.2mb/sec we don't have any problems at all with disk through
put.  If we want to have 48 tracks we would need only 18mb/s.  Not to hard
to do by any means.  

So what were you getting at?

     Frank Carmickle
phone:     412 761-9568
email:     frankiec at dryrose.com

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