[OBORONA-SPAM] Re: ipod madness

Art Alexion art.alexion at verizon.net
Tue Apr 25 14:08:32 UTC 2006


I'm no expert on this, but I think you are on the right track, but have the 
details wrong, perhaps backwards.

In the FAT file system, files are stored in blocks of a fixed size.  Sometimes 
you can control that, but the larger the disk, the less control you have as 
the File Access Table (FAT) can only contain a fixed number of entries, so 
the bigger the disc, the bigger the size of the blocks.  FAT32, introduced in 
win98, was an improvement over FAT16 (win3.1-win95), because the table size 
increased, allowing more blocks (and with that, potentially smaller blocks).

With FAT, a file can be spread over multiple blocks, but multiple files cannot 
share a block. As soon as a file uses one byte of a block, the block is 
completely used as far as other files are concerned.

Efficient use of blocks is a matter of happenstance, the idea being that the 
fewer low use blocks, the more efficient the storage.

With large blocks, this can be a problem because, in your example of 64k 
blocks, a single byte from a file will take up that entire 64k.

Wile the effect is less with, say, 10MB of larger music files (1-3 files) than 
with 4k text files (2500 files - each one contributing some slack), it is 
still more efficient to go with the smallest block size possible.

Analogize it to phone charges.  In the US, some companies bill in 1 minute 
increments and others in 6 second increments.  It is always cheaper to have a 
service that bills in 6 second increments because a 61 second call is 
otherwise billed as 2 minutes (120 seconds) versus 66 seconds.

On Tuesday 25 April 2006 03:56, Gabriel Dragffy wrote:
> This could be due to "cluster slack" with the fat32 fs. You have probably
> formatted it with very small clusters of maybe 4k? This is well suited to
> text documents and relatively small files, but will be inefficient when
> using lots of large files (like mp3s). Best bet is to check what cluster
> size it is at the moment and adjust it to something like 64k if it isn't
> already there. I only know of one tool that can do this to drives without
> reformatting them in the process "Acronis Disc Director" or "Acronis
> Partition Expert". In the worst case scenario you could be wasting 10-20%
> of space by using very wrong cluster sizes.
> Has anyone noticed in wind**s when you look at a files properties it give
> you two sizes - the first is the size of the file and the second is the
> size it takes up on disc (with cluster slack taken into consideration). As
> it turns out the second figure is always almost larger.
> I know that on Linux the ReiserFS doesn't suffer from this or XFS (I
> haven't research ext2/3 or JFS) and judging from what you're saying HPFS
> also avoids this problem.
>
> Gabe
>
> > i have finally been using only gtkpod to sync my ipod back and forth. i
> > have discovered one odd issue: since reformatting to vfat i don't seem
> > to have as much space left. the same amount of music (roughly 2,000
> > songs) on the apple file system (using itunes) took less than 1/2 of my
> > 20 gig ipod's space. now using vfat the same amount of songs (using
> > gtkpod) takes over 3/4 of my space. is there something going on with
> > either the format or gtkpod?

-- 

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