varying speeds when copying (fixed during copy)

[eydaimon]

Hi, I just upgraded to 7.04a although what I am about to report I have found to happen in various other versions as well.

I was copying some files to my microSD drive. The files copied at about 5mb/sec.

After some more copying back and fourth, the files suddenly started copying only at 148kb/sec. A reboot later, same thing.

I used windows file manager (yuck) and copied the files, which gave me a transfer speed of about 7mb/sec.

I then tried TC again, and this time I got 3mb/sec. One more try, and I got 5mb/sec. Same file, copying several times.

I still get around 7-10mb/sec using windows file manager (yuck). Why is this happening?

[sqa_wizard]

I then tried TC again, and this time I got 3mb/sec. One more try, and I got 5mb/sec. Same file, copying several times.

I still get around 7-10mb/sec using windows file manager (yuck). Why is this happening?

Different copy speeds may have various reasons.

One of them is the transfered file size.
1 file with 100 MB will be copied way faster than 100 files with 1 MB (due to interrupting copy process for reading/writing FAT entries)

Another one is a virus scanner who intensively scans the accessed files AND the parent process (TC or Explorer)
=> try to disable your virus scanner for testing the difference (if it helps, exclude TOTALCMD.EXE from scan)

Finally the copy method used may not work best for this microSD drive destination.
=> Set mode by menu "Configuration - Options - Copy/delete: Use compatibility mode for the following drives" and add drive letter of your microSD drive.

[eydaimon]

Same file, copying several times.

Quoting myself here, but I want to make the point that this is the same file that's being copied with both TC and windows file manager (WFM).

Viris scanner shouldn't make the difference, but this copy method may very well.

I could see how the copy method would make a consistent difference between the two FMs but not why TC itself is sometimes fast, and sometimes slow, on the same file.

Thanks much.

[sqa_wizard]

TC itself is sometimes fast, and sometimes slow, on the same file.

A file is usually cached. TC writes to this cache (RAM) until it is full.
At least the first part of a file is written very fast this way. Later, when the data is REALLY written to media, the speed decreases.
Small files may fit completely into this cache and the copy operation seems to complete very fast ... at least the operating system tells you that it has finished, although the data is still at RAM and will be written delayed.

[eydaimon]

The interesting part is that the first file I copied was very fast. I disconnected the USB drive, discovered I had missed a file and reinserted it. I copied another file, and this one was extremely slow. After waiting several minutes, I gave up. i.e. 145kb/sec vs. 5mb/sec

That's a big difference in speed, and I don't see how caching makes up for that. Certainly after several minutes I should see a speed increase if this was due to caching, but it was not so. The files I copied were 60-120mb files. Small files these days, I suppose, but still, it should not take 5+ minutes to copy one of them.

[sqa_wizard]

I disconnected the USB drive, discovered I had missed a file and reinserted it.

Probably this was the cause of slow down. A "new" drive is always very interesting to an eager Antivirus or even Windows indexing service.

I had a bad experience by just disconnecting and reconnecting my USB-Stick.
First did a "Safely Remove Hardware", which worked fine.
Then I was unsure, if I had copied a file, reinserted it, saw the file and did a "Safely Remove Hardware" again, which was refused this time.
I tried it once more with the same result and after some minutes I decided to take a deeper look who was locking it.
To my surprise it was the "On access scan" of my antivirus, though no application was accessing anything on this stick.
Just stopping the scanner unlocks it.

To shorten it: If you reinsert a device, you may have to share the bandwidth with your antivirus ...

[eydaimon]

ah, I had not considered that. And the very first I inserted it, it was completely empty, so it wouldn't have taken any time to do a scan.

The transfer rate "from" the device was 13mb/sec though. But only write was slow. Any ideas why that would be?

This theory doesn't explain the fact why copying within WFM was unhampered by the antivirus program, and could continue at the 8mb/sec transfer rate.

[sqa_wizard]

why copying within WFM was unhampered by the antivirus program

Well Windows explorer is a "native born child" of windows
This means windows and even antivirus programs trust it by default.

To tell your antivirus to do the same with TC, you have to exclude TOTALCMD.EXE from "On Access Scan".
Don't worry, this is quiet save. TC has an internal CRC check and will detect any modification ...