Verfication during/after copy/move

[roman2]

According to http://www.ss64.com/nt/verify.html, Windows is able to verify file copy/move. Does/can Salamander verify correctness of these operations?

[cincura.net]

According to http://www.ss64.com/nt/verify.html, Windows is able to verify file copy/move. Does/can Salamander verify correctness of these operations?

No AS isn't doing some checking (running verify command). You can do this using i.e. File Comparator and/or Checksum plugin.

[roman2]

Then it would be good to have an option to do this automatically.

[cincura.net]

Then it would be good to have an option to do this automatically.

How often you think users will use this function? Apart from that one hotkey can solve this easily - how hard can it be navigate into these folders and press Ctrl-Shift-C or use Checksum plugin (hotkey can be also assigned).

[roman2]

Much more often than what you suggested, I am sure. Your suggestion requires an extra step (or several), but mine -- only setting an option. And these extra steps are out of the question for non-geeks. I, for one, want all my file copying/moving to be as reliable as possible. And I want other people who copy files for me to give me uncorrupted files.

Think "user friendliness", not "less work for Salamander developers".

[Tomas Kopal]

The VERIFY ON command is a relict from the old DOS times. What it does is that after every copy it reads the source file again, reads the destination file again, and compares them. That means that the copy operation takes approximately three times longer than normally. I do not know anyone who used this option in the old DOS days, as this speed decrease was unacceptable, especially as the probability of an error during copy is pretty low. And the disks are now much more reliable than at that times.
I think that it works only for command line copy command, not for explorer or any other way of copying, so be sure to use the right copy command when testing it.
Try playing with the option to see if it is usable for you. I am almost sure that you too find this unusable and you won't pursue this request further...

[ino]

Does/can Salamander verify correctness of these operations?

roman2,
Salamander can:
- compare two files if they are the same with Compare File feature use Ctrl+Shift+C
- compare two direcrtories with Compare Directories feature use Ctrl+F10. For more info check F1 for help and search Index for keyword "Comparing".

Both can verify if the source file/directory is the same with the destination file/directory including subdirectories.

Hope it helps a bit

[roman2]

ino, I am aware of these options, but neither are convenient enough. I just to be able to copy/move files and be sure that the operation took place correctly. The options you suggested would take even longer than what Tomas said would be required for operations with the verifying option.

Tomas, how low is "low" and what would you do if you lost important files? Sometimes taking more time for higher reliability is justified.

[cincura.net]

ino, I am aware of these options, but neither are convenient enough. I just to be able to copy/move files and be sure that the operation took place correctly.

But you can. In fact, with checksum plugin you can do more (i.e. save MD5/... for later usage).

The options you suggested would take even longer than what Tomas said would be required for operations with the verifying option.

No. If I'll not be taking into account overhead of pressing some hotkey, it will take exactly same time.

[roman2]

Extra clicks and key presses are important. And your way requires selecting files to be compared after the operation. That's prone to mistakes (because files can be missed). That's in addition to click/press overhead. It's MUCH easier to select files, press F5, check the verify option, click OK, and be done with it.

Think user-friendliness!

[zarevak]

Hi, I just want to remind you few important issues with Verify option:

1) The Windows are multi-tasking, multi-user, multi-everything operating system. The source (and even the destination file) file can change dramatically each second by another process or another user. If you try to verify it you could get an error message saying the file is different even when it was copied without problems.

2) Windows (and other modern operating systems) are using caches for reading and writing to disk drives. Even when Salamander would close the file and open it a few moments afterwards the whole data could still be present only in the cache and thus you cannot test if they will get written properly. (This is the reason for Safely remove removable devices icon in notification area when you connect a flash drive using USB - it flushes the caches and guarantees all files are written and closed properly)

[Tomas Kopal]

I completely agree with Zarevak here. The option would just add a false sense of security.
If you want to be sure your data are always safe, buy reliable hardware.

[roman2]

If you want to be sure your data are always safe, buy reliable hardware.

This is impossible. However, Zarevak does have a point.

[Tomas Kopal]

If you want to be sure your data are always safe, buy reliable hardware.

This is impossible.

Why? Have you ever heard about technologies like DIF? Have ever used RAID arrays? About redundancy of controllers, parity controlled memory etc? That is the way to ensure your data are always safe.
Software can never guarantee that alone. What if the same read error happens when you read a file for verification? You got positive check, but you still have corrupted file...

[zarevak]

This is impossible.

Why? Have you ever heard about technologies like DIF? Have ever used RAID arrays? About redundancy of controllers, parity controlled memory etc?

Mathematically it's impossible to have your data "always safe".
First: Parity data on most systems can just detect errors, but could not do complex repairs.
Second: Let's say your hard drive has 99,99% success rate at reading/writing your data correctly. If you put two mirrored hard drives in RAID you will get 99,999999% success rate, but this is still not 100% guarantee your data are safe. More disks you add to your raid the probability of error decreases, but there will always be a slight chance of failure of the system.