After updating the version, the synchronization speed is much slower

[guoh27]

Now I am using version 12.1, and I feel that the synchronization speed of recent versions is much slower than simply copying and pasting files

this is FreeFileSync screenshot (5MB/s):

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this is windows explorer copy progress screenshot (39MB/s):

微信截图_20230402171758.png (2.96 KiB) Viewed 1215 times

Their source and target disks are same, so it shouldn't make that much of a difference.

[Plerry]

By default, FFS uses "Fail-safe file copy" (found in the FFS Options). This creates an overhead compared to "simply copying and pasting files", especially if pre-existing files are overwritten by your sync.

And obviously, in case you would have set the VerifyCopiedFiles flag to True (?), all your sync actions (except deletions) will become notably slower.

[xCSxXenon]

It could also be the File Explorer and FFS aren't copying files in the same order. You need to perform tests that time a whole set of data being transferred from start to finish, not just mid-sync.
If it is still not meeting expectations, revert to the previous version and see if it goes back to normal, report back

[guoh27]

I found something very strange

The same source folder and destination folder, but the synced files are different, the speed difference is huge

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Their file types are also the same (mp4), renaming does not affect the results, but the file copy version speed is normal.

I tried from version 12.2 to 11.23 with the same result,
So it's a problem with this file

I don't know how to solve this problem.

[therube]

If you try to copy that file using Windows Explorer (or similar), is that also slow?

(Far fetched I might think, but) might it be a fragmentation issue?

You can throw contig, with the -a switch, at the file & it will tell you the number of fragments.
https://learn.microsoft.com/en-us/sysinternals/downloads/contig

C:\> CONTIG.EXE  -a  testfile.mp4

C:\testfile.mp4 is in 2 fragments

Summary:
     Number of files processed   : 1
     Average fragmentation       : 2 frags/file


[guoh27]

No, it's not about fragmentation.

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[guoh27]

Both https://fastcopy.jp/ and Explorer doesn't have this problem.

This is Fastcopy screenshot

微信截图_20230404225809.png (4 KiB) Viewed 1109 times

[guoh27]

It should be mentioned that this will only happen when copying to different disks, and it will not happen when copying to the same disk.

Both are mechanical hard drives.

in conclusion:
Some files will be more than 5 times slower when using FFS synchronization across disks.

And I tried disable "Fail-safe file copy", didn't work either.

[guoh27]

It may also be related to the write strategy of FFS to the target disk. Using FFS to synchronize two files, both are 100% loaded, but the writing speed is different.

Here is a screenshot of my task manager (Forgive my task manager is Chinese, But you should also be able to see 100% load and 11M/50M write speed)

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微信截图_20230405001521.png (40.12 KiB) Viewed 1080 times

It's a Western Digital WD Purple Harddisk, mostly used for surveillance applications.

[therube]

both are 100% loaded

Loaded as in there is virtually no free space left on the drives?

Do you have 'Fail-safe file copy' enabled?
If so, you would need 2x the file size of free space.

[guoh27]

both are 100% loaded

Loaded as in there is virtually no free space left on the drives?

Do you have 'Fail-safe file copy' enabled?
If so, you would need 2x the file size of free space.

It meas hard disk activity time reaches 100%