SQUIRE wrote:Firstly, if you have a flaky power supply then all bets are off, irrespective of whether or not there is a verify-after-copy facility.
All subsystems in the PC cannot now be relied upon to function correctly.
All subsystems WORKED CORRECTLY except the power to this 1 hard drive.
SQUIRE wrote:That fault could quite easily (and more likely in my opinion) have affected the PC's RAM causing bad data to be transferred to the HDD.
Whatever the reason is: CRC verification caught it.
SQUIRE wrote:You would not know unless you were using ECC RAM and even then multiple bit errors can cancel out. Doing a read-after-write back to the same intermittently faulty RAM might show no errors. So how would a verify function protect you?
I DON'T CARE WHAT CAUSED IT.
That is not the point.
The point is that you MOVE GIGABYTES OF DATA which arrive CORRUPTED.
CRC checks catch it. They ALARM YOU. They make it possible to REPLACE malfunctioning hardware. NOT LOSING YOUR DATA is the target.
SQUIRE wrote:Secondly, was your screen capture taken on the same PC before you discovered the failing PSU? In that event even the snapshot you see could as easily be invalid for the reason given above.
You make a logical fallacy here:
Whether the
* COPIED file was CORRUPTLY WRITTEN
* or the copied file was not corrupt (merely CORRUPLTY READ)
* or the ORIGINAL file was CORRUPTLY READ
* or the ORIGINAL file was CORRUPTLY TRANSFERRED
is IRRELEVANT for catching the hardware culprit. As soon as CRC errors occur you know that something is wrong with the hardware: Cables, sockets, hubs etc.
Without CRC checks you wouldn't even notice. Maybe even for years, if you use a faulty LAN hub.
And no, I checked the file several times after I replaced the faulty hardware: With the same results: Complete corruption.
I can't believe that after 60+ posts I still have to point out OBVIOUS FACTS: Copy errors _DO_ HAPPEN. Whether you like it or not. Due to hardware or software or whatever.
Get over it.
And I can't believe that I paid for Total Commander (whose MOST SIGNIFICANT PURPOSE is to copy files) and yet I have to rely on third party solutions to make sure that my files are copied correctly.
TC has functions which hardly anyone uses like "Overwrite if larger" but lacks a real safety function like a simple checkbox "[x] CRC check copied files".
SQUIRE wrote:In my experience, normal day to day error detection does a perfectly adequate job of flagging faulty cables and peripherals without going into extreme paranoia mode.
So you admit that you don't do CRC checks. In other words: You have no clue how many of the files you have ever copied arrived 100% intact, yet you make bold statements about error detections.
Look, you can choose to not verify your files as much as you like. I don't care about your files. But speaking for myself: I want a CRC option.
SQUIRE wrote:If you need near 100% guaranteed error-free results then you really ought to be using a hardware solution with redundant subsystems. A software verify function can only provide a false sense of security.
Unbelievable. I gave already examples how CRC checks CAUGHT SIGNIFICANT data corruption and I have to read such excuses that "it only provides a false sense of security".
You are basically claiming "Inspections of airplanes provide a false sense of security". Yeah, but what you conveniently failed to mention is that inspections indeed can prevent crashes.