Detecting file changes at block or byte level

[Joshua Jung]

Hi, I am currently doing some research on building an app to send files
over a network. We are wanting to only send changes in files if the file
is already on the other computer.

Is there a way to *quickly* detect changes between
the file on the other computer (server) and the computer we are sending
from?

I have looked into polling, but unfortunately, polling just lets us
know if the file has changed. We need a way to detect block level (like on
the hard drive) changes or have the OS (Windows, Unix) send us details on
files that are being changed and where in the file something has been
changed.

Any help, links, or suggestions would be greatly appreciated

and I hope I posted on the write newsgroup...

Josh <><

 

[Rogan Dawes]

Hi, I am currently doing some research on building an app to send files
over a network. We are wanting to only send changes in files if the file
is already on the other computer.

Is there a way to *quickly* detect changes between
the file on the other computer (server) and the computer we are sending
from?

I have looked into polling, but unfortunately, polling just lets us
know if the file has changed. We need a way to detect block level (like on
the hard drive) changes or have the OS (Windows, Unix) send us details on
files that are being changed and where in the file something has been
changed.

Any help, links, or suggestions would be greatly appreciated

and I hope I posted on the write newsgroup...

Josh <><

rsync

 

[suken]

Hi,
If you just want to decide if you want to copy it or not then you
can compare the created dates for both the files and decide if the
target file is of a later date then copy the file.
Also there is an algorithm called sliding window algorithm which i
think will help you with the changes in file you can goole it.

Regards,
Suken Shah

 

[shashank929]

Help required for detecting file changes at block level

Actually I'm making a simple program for detecting the duplicate content between two files at the block level ........ the two files are on the same system so I thought that studying rsync would help me.... I downloaded it's source code but it's not easy to understand and is also not documented very well.....

So can anyone help me regarding this...... especially what block size to choose depending upon the size of the file.....
or can give me link where I can any such code....

 

[dealbaaj]

Large file replication on byte level

Gurus,

I am looking for a utility which can help me replicate a large LUN file (device file) over the wire. The file content are continuously changing and so I would like to do a byte level comparison, store the comparison blocks at the destination and perform another comparison and syncup the changed bits only. I am talking async replication of 1TB files.

Somebody talked about Sliding Window algorithm, can you point me to such a utility ?

 

[dealbaaj]

Hi,
If you just want to decide if you want to copy it or not then you
can compare the created dates for both the files and decide if the
target file is of a later date then copy the file.
Also there is an algorithm called sliding window algorithm which i
think will help you with the changes in file you can goole it.

Regards,
Suken Shah

Hi Suken,

I am looking for a utility which can help me replicate a large LUN file (device file) over the wire. The file content are continuously changing and so I would like to do a byte level comparison, store the comparison blocks at the destination and perform another comparison and syncup the changed bits only. I am talking async replication of 1TB files.

Somebody talked about Sliding Window algorithm, can you point me to such a utility ?