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Therefore, to properly verify, you must clear the cache.

The problem is that if you cache the files during transfer, the comparison becomes useless because you are not reading the actual data on the destination drive, you are reading the copy cached in memory from the source. If hashes matched and not finished, go back to step 1.If hashes don’t match, give error and prompt user for action.Hash the chunk from the destination drive.Read the chunk back from the destination drive.Hash the chunk read from the source drive.Look at what happens when you copy a file with Teracopy (with an HDD-optimized algorithm):

#Teracopy windows 7 ultimate download verification

Unlike Explorer which only checks for basic errors during the transfer, Teracopy can actually verify that the data was written correctly to the destination drive in order to prevent data corruption which could happen due to problems in the transfer media (network/drive cable/etc.) or the drive itself (bad sector, etc.) Doing this means that it has to read the file from the destination to compare it to the original.ĭepending on the algorithm used and the size of the file, verification can be optimized as low as (but no less than) three drive operations for each file/file-chunk as opposed to Explorer’s two: read the file from the source, write the file to the destination, and read the file from the destination. Verify that the destination was written correctly Teracopy can do two things that can slow down a file transfer which Explorer does not do:įorgo the cache and read directly from the drive Since memory is very fast, and read speeds tend to be a little faster than write speeds, the ultimate transfer rate ends up being limited only by the write speed of the destination drive. The comparison will be much faster at that point than if you do it later on because the file(s) are still in memory, so it is not actually reading them from the drive(s). You can see the caching in action by copying a large file-or a folder containing a lot of files-from one drive to another, then immediately comparing the two.

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Obviously this can’t hold up forever, but Windows can use up all remaining free memory as a temporary buffer to store most, if not all of the the file that is being read in memory. So instead of waiting for the previous chunk to finish getting written, and then reading the next chunk, a new chunk can be read while the previous one is still being written. With this transfer algorithm, each byte of the file is gets processed only two times: one read, one write.īut in addition, Windows uses memory (as does the drive itself) to cache some data.

Write the chunk to the destination drive.

Read a chunk of data from the source drive into memory.

This is the general procedure for copying a file with Windows Explorer:

Two words: verification and cache Technical Explanation

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Over gigabit connection, Teracopy does 31MB/s, but Windows 8 does it at ~109MB per second? What exactly is causing this? And can I enable such speeds via Teracopy? I really dig the extra features that Teracopy has, will surely miss them now :D I then stumbled upon this little piece of info after which I turned off Teracopy and copied the same file through Windows 8's regular copier.

So just for the sake of doing it, I iPerf'd both the systems and guess what that showed - around 875mbps on both systems! Although satisfied with the 30-34 MB/s that Teracopy was showing (that was a proper step-up for me from 10 MB/s), I still was curious about this massive difference in the advertised and real-world speed.Ģ hours of Google had me believing that there were other factors that resulted in less speed, SMB being one.

#Teracopy windows 7 ultimate download mp4

I got my brain-melting first taste of Gigabit networking today, between my 2011 MacMini and Windows 8 Pro desktop connected via Cat.5e to Linksys WRT320N(sporting dd-WRT).Īfter making sure that the line speed on both systems showed 1Gbps, I proceeded to copying a 2.4GB MP4 from the Mini to the Win 8 desktop (SMB sharing).