Going about beta-testing a program... advice?

[Madison Kelly]

Lennart Sorensen wrote:
> I suspect you may have misunderstood how rsync works.  Rsync only
> transfers changes when doing work over a network link, by reading the
> whole file on each end (unless other things like time stamps and size
> and such match perfectly in which case it assumes they are the same),
> and calculating checksums to figure out what to transfer over the slow
> network link.  When rsync is run locally to transfer between disks, it
> simply checks the time stamps and decides if the file has changed or
> not.  It would not make sense for rsync to do it's efficient over
> network algorith since it involves reading both files entirely,
> calculating checksums, then writing a new copy of the file on the
> destination, reading from the original destination and filling in with
> updates from the other as it goes.  When done the new file is renamed
> over top of the original destination file.  Doing this would not save
> disk activity, on the contrary it would require reading two files and
> writing one file completely instead of a simple copy which is one read
> and one write.  This is why rsync run locally simply does a copy if it
> sees that a file is changed.

   There is a switch for rsync that tells it to do delta copies on local 
file systems. What you say though is quite valid and I will need to run 
performance tests later to see which is actually more efficient. I 
enabled the switch by default (you can tweak how rsync runs in the 
config file) thinking about some files that where several gigs in size.

> Does it backup all relevant attributes of the files?  Extended
> atributers (filesystem specific)?  ACL?

I haven't recorded ACL (to make sure I understand, you are talking about 
MS NTFS extended data, right?) however now that you mentioned that I can 
get that info using 'getfact -R' I should be able to add that easily 
enough. Making sure that I get everything relevant will be part of the 
beta-testing process. At this point I record owner, group, permissions, 
last modified date and time, size, etc...

> Well it sounds decent.
> 
> I use tob (tape oriented backup) with afio archives, splitting into 1GB
> pieces that I then burn to DVD (4 pieces per DVD).  I archive acl info
> with getfact -R and dump to a file and burn that seperately.
> 
> Restores simply require a linux system installed with fielsystem, and
> afio available.
> 
> Lennart Sorensen

   Thanks for your input! I am finding it a lot harder to get help and 
feedback then I expected. I suppose I should have expected that given my 
boss' desire for a non-GPL license. I had hope making it free to home 
users was enough though I have to admit if I was on the other side of 
this I may well feel the same as others here seem to feel. Alas...

Madison
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