Comparison takes much longer

[F-Kae]

Hi,
I am using FreeFileSync now for about one year and I am really happy with it! But for any reason I am struggeling with the comparison now since two weeks. The comparison suddenly took more than 3 hours until I stopped this procedure. It seems like happening all the time when reaching 160000 files compared. The first 160 thousand files comparing in about 1 Minute and than the speed slows dramatically down!
I think I want to synchronize about 300000 files in total.

Setup:
FreeFileSync 7.9
Windows 10
External Disk 1,5TB (300000Files ~1TB)
Sync to WD MyCloud 3TB
LAN connection of Laptop and MyCloud to HorizonBox from Unitymedia
Compare for FileName and Size

I am afraid it will be hard to identify my issue but maybe someone have any idea :)

Greetings,
Florian

[pete.goss]

Hi,

I’m also experiencing very slow drive comparison on Windows Vista, using Freefilesync 7.9. Version 7.8— which I reinstalled— remains as speedy as ever.

Here are the specifics:

I am comparing a folder on C:\ (approx 25,000 items) to the same named folder on my external hard drive (BUFFALO HD-LXU3 USB DEVICE, designated as my f:\ drive). I have Freefilesync set to mirror the folder on C:\.

Version 7.9: 12 minutes to complete. C:\ drive takes less than 1 minute to scan, but the f:\ drive “drags”.

Version 7.8: completes in less than 2 minutes; speed remains consistent.

I’ve checked the external drive and it’s fully operational. Any idea why 7.9 is so much slower?

Thanks….

[Zenju]

There haven't been any changes to the comparison and copy routines between 7.8 and 7.9, so any perceived differences are likely incidental (or a systematic error during the measurements).

[pete.goss]

Hi Zenju,

Thanks very much for your reply, but neither “perception” nor “systematic error during the measurements” explains what I am seeing.

I reloaded 7.9 this morning. It took FreeFileSync 8 minutes to complete the sync. I actually sat there and timed it independently. Next, I reloaded 7.8; it took less than a minute to sync!

So while I believe you that the comparison and copy routines did not change, another change somewhere else is likely causing the problem. I’d be willing to do more testing with you if you like, or I can just wait to see if version 7.10 works better whenever it is released.

In any event, FreeFileSync still works better than any alternative to it, and I am grateful for the program and your effort.

Pete

[Zenju]

I reloaded 7.9 this morning. It took FreeFileSync 8 minutes to complete the sync. [...] Next, I reloaded 7.8; it took less than a minute to sync!

That's what I meant with systematic error. After syncing with 7.9 the OS-internal file system buffers are filled, so naturally the next sync with 7.8 will finish faster.

[F-Kae]

I even reinstalled FFS7.6 without any difference in speed.
What seems weird to me is this "magic number" of 160,000 files. It always begins to slow down when reaching this number of compared files and it won't speed up since than again...