General Question

rovdog's avatar

I have to do a one time data transfer of a lot of data. Is it best just to use my mac and copy over using the finder or to use a backup solution like Carbon Copy Cloner?

Asked by rovdog (842points) December 27th, 2010

I have to make sure that the transfer goes smoothly and the backup is not corrupt. But I have no need to do on-going backups I just need an exact copy of this data on another drive. I would like to verify that all the data made it over. Are there any advantages that something like Carbon Copy Cloner, Intego Backup Assistant, or other backup programs have over doing simple the copy application in OS X? If I do that- is there a simple way of verifying the files? It is a simple copy of a lot of data but in very few folders, so selecting it and copying it over is certainly an option.

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5 Answers

Vortico's avatar

I would personally use the command line for something like this (cp -rf <source> <destination>), but Finder will work fine for your purposes. Unless you’re copying files without appropriate read permissions, the backup will go smoothly.

rovdog's avatar

I think all permissions are read and write. I’m considering using carbon copy cloner to clone block by block- any advantage? Actually I’m wondering if there is any downside to backing up the data this way.

rovdog's avatar

Some resources from my own research- in case anyone is wondering the same thing (WOULD still love answers!)

This is from the Carbon Copy Cloner website re: the difference is drag and drop and using CCC for this application- basically CCC is slower but can clone block by block which is always faster than file level copying

Advantages or disadvantages of block by block copying versus file level copying are discussed here. Basically, block by block is thought to be better for large amounts of files and where permissions can be a problem

Vortico's avatar

How big is “a lot of data”? I personally wouldn’t have much of a problem backing up a terabyte of data, but if it’s truly important enough to have the need to verify, it should just be backed up on multiple sources in different locations.

But here’s an idea: You could calculate the checksum of each folder and compare them against each other. Try running “tar -c <directory> | md5sum” on each of the huge folders after copying and compare the results.

rovdog's avatar

Thanks @Vortico I started a carbon copy cloner block to block copy and wasn’t confortable with it so I cancelled it, reformatted and copied over the files using the finder. I compared the file sizes of all the sub directories and number of items and they all match.

I have to look through an old question- someone had walked me through how to compare two folders using the terminal. I will try your method as well. I also have a program called diffmerge but I’m not comfortable with it yet- I’m a little confused by the results. I’m surprised there isn’t any easy way of comparing folders in OS X without the terminal- seems like it is a common need.

It’s 2 TB of data. It’s backed up multiple ways- I am copying it to a mirrored raid and this is part of my offsite plan. I just want to make sure I’m not storing bad data, especially on the raid.

BTW The biggest thing about I learned about block to block copying is how it solves permissions problems- seems like that might be why CCC is useful for migrating to a new computer. I’ve run into permissions problems using Migration Assistant.

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