Copy Methods

vp · Post by vp » 25 Jun 2005, 23:25

I have been using AllSync for a few days, and the backups are really slow. My needs are as follows: I am backing up a remote site (over VPN) to a local hard drive (let's call it "task X"), and I am also backing up a local drive to a NAS on the local network (let's call it "task Y"), both with copy method B, which is the default for Windows 2000.

I think I could save a lot of time by unchecking the "Overwrite file if the content of the files is different" option. With this option enabled, AllSync must scan each entire file for differences, wasting precious time. If the program doesn't check contents, each file check will take almost no time, no matter how large the file is, unless it actually must be copied.

Is the above theory correct?

Second, your statistics show that copy method B takes significantly longer than the others over a network. I don't want to lose all interactivity, so I don't want to use method A. I also noticed that method C takes longer than the others with a USB stick.

Which method do you recommend (i.e. which is fastest) for "task X", and which for "task Y"?

Assuming you're going to say method C, what settings should I use? Of course no pause, but what would be the optimal data packet size?

Thanks

Post by **Administrator** » 26 Jun 2005, 01:30

If the program doesn't check contents, each file check will take almost no time, no matter how large the file is, unless it actually must be copied. Is the above theory correct?

Yes.

Which method do you recommend (i.e. which is fastest) for "task X", and which for "task Y"?

For "Task Y" i would use Copy method C. For "Task X" i don't know. You have to test the VPN with Copy method B and C.

Assuming you're going to say method C, what settings should I use? Of course no pause, but what would be the optimal data packet size?

To find out the optimal data packet size you must do some copy tests with your connection (VPN, USB, Wireless...)

vp · Post by vp » 02 Jul 2005, 06:51

Can you provide more technical information about copy methods A, B and C?

Post by **Administrator** » 02 Jul 2005, 19:21

which technical informations do you mean? the name of the used APIs?

vp · Post by vp » 02 Jul 2005, 23:31

Yes, that would help. I'd like to do research on which method would work better for me in various situations. Thanks!

Post by **Administrator** » 03 Jul 2005, 15:55

copy methode A uses the API "copyfile"

copy methode B uses the API "copyfileex"

copy methode C uses the API "CreateFile"

more infos about the APIs:

http://msdn.microsoft.com/library/defau ... ctions.asp

vp · Post by vp » 03 Jul 2005, 21:37

Thanks!

vp · Post by vp » 22 Jul 2005, 04:43

What is the maximum packet size possble? What is the significance of this number, and are there limitations to packet size based on protocol or other parameters?

Post by **Administrator** » 22 Jul 2005, 16:33

vp wrote:What is the maximum packet size possble?

At this time its limited to a max. value of 999.999 bytes. If you need more.

What is the significance of this number,

This number specify the data packet size used to read from the source file to the memory and then write from the memory to the destination file.

and are there limitations to packet size based on protocol or other parameters?

Maybe, i think a packet size of 999.999 bytes will not very usefull with a slow modem connection of 64kb....you have to do some copy tests to find the optimal packet size.

vp · Post by vp » 23 Jul 2005, 05:13

The Ethernet maximum packet size is 1500, so is it perhaps pointless (or even counter-productive) to set the value any higher than that if transferring between computers?

Post by **Administrator** » 23 Jul 2005, 16:08

Maybe...have you tested this value (compared with the standard value)? Any differences?

vp · Post by vp » 24 Jul 2005, 01:19

Give me some time and we'll see...

AllSync & AllDup

Copy Methods

Copy Methods

Re: Copy Methods