[Gambas-user] Binary compare of files?

[Doriano Blengino]

Kari Laine ha scritto:
> On Sun, Oct 19, 2008 at 7:02 AM, nando <nando_f at ...951...> wrote:
>
>   
>> but use a large block size
>> like 8192 or 32768.  It doesn't have to be a perfect binary size.
>>     
True, it does not have to be a perfect power of two, but I suspect that 
good boundaries optimize disk reading (well, this is of scarce 
importance while checksumming with a complex algorithm).

> Also there is lot of duplication in disks I dont't want same data backed up
> many times on DVDs. By the way does anyone have an idea how long lived a dvd
> is?
>   
I don't know much DVDs, but I know for sure that CDs are about the worst 
media in respect of indurance. I've read an article which compared 
media: paper is not bad (hundreds of year), those old documents written 
on animal skins (don't know the name in english) endure thousands of 
year. Nowadays, magneto-optical media are good - they need both magnetic 
fields and laser together to be written/erased, while harddisks and 
floppies (zips included) suffer from magnetic fields, and CD/DVDs suffer 
light, dust, physical damage, heat - everything. CD/DVDs are not true 
randomly writable (ok, perhaps for backups it doesn't matter).
Anyway, the expected life for a CD was seven (7) years. I think DVDs are 
near to that.

Flash memory is very good - it suffers nothing (apart lightning), 
unfortunately is expensive.

Anyway I have always hated CDs and DVDs, almost the same as I hated 
floppies; totally unreliable. It is happened to me to go to a customer 
carrying three (3) copies of the same data, just to find that noone was 
good, thanks also to the poor implementation of PCs hardware...

But seems that everybody trusts CDs, so may be I am wrong.

Salut,
Doriano