[hfs-user] Problem of Allocation Block Size

Patrick Dirks pwd@apple.com
Tue, 30 Apr 2002 10:27:45 -0700


Hi Biswaroop,

You're right; HFS limits the number of allocation blocks to be somewhere 
between 2^31 and 2^32 at best, which forces allocation block sizes to 
get larger and larger as the disk size goes up.  This problem, and the 
resulting waste of space, was one of the factors that drove the 
development of HFS+ which can work with much smaller allocation blocks 
than HFS for a given volume size.

-Patrick.

On Tuesday, April 30, 2002, at 04:00 AM, Biswaroop(External) wrote:

> Hi,
>
> When I create a volume of bigger size for eg. 640 MB
>
>   Now since allocation units is fixed at 65536.
>   Therefore
>   Bytes per allocation unit becomes
>    640 * 2 ^20 / 65536 = 10 * 2^10 (10K) (approx)
>   That means if i give even one allocation block
>   for each file i am physically giving him 10k space
>   even though file may be some 100 bytes which
>   results in space wastage.
>   I  also believe there is no solution because each
>   file should have atleast one allocation block
>   and each file should start from a new allocation
>   block .
>   I am just wondering if I am right???
>   Or there is some alternative!!
>   Waitng for ur comments.
>    regards
>    Biswaroop
>
>
> The difference between sunrise and
> sunset lies in the freshness of your
> eyes.
>                                   --Bisban
>