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Writing more than 5 GB to a USB thumbdrive is much slower on 24.04 when compared to 22.04. What action might bring the transfer rate on 24.04 in line with that observed on 22.04?

Using hardware of identical configuration (Dell 7020 desktop), one loaded with Xubuntu 22.04, the other with Xubuntu 24.04 and two identical thumb drives. The thumb drives are formatted NTFS and cleaned prior to each test run. The thumb drives are referred to here as PEACH and ARCTIC. The data being copied resides in several files on the primary harddrive of each system. The size of each file ranges from a few bytes to one at 3.3GB.

22.04 took 9 minutes to ARCTIC and 10 minutes to PEACH 24.04 took 127 minutes to ARCTIC and 142 minutes to PEACH

At first, 24.04 was reporting the copy function complete quite a bit faster than that measured on 22.04. Once the accumulated total of data reported copied reached about 5GB, 24.04 became very slow.

An additional pair of runs was made using PEACH after adding the command sync just prior to completion. Those run results are:

22.04 took 30 minutes total with sync - sync itself took 21 minutes 24.04 took 175 minutes total with sync - sync itself took 10 minutes

A similar thumbdrive, formatted ext4 took 47 minutes on 24.04 of which the sync was 10 minutes. This same ext4 formated drive took 34 minutes of which the sync was 11 minutes.

quill
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  • Search this site for "slow copy" or "data transfer" and see the many problems, with suggestions which may improve specific situations. Basically, when the reads are faster than the writes, system buffers fill up, dragging things to a crawl. The sync show how long it takes to flush the system buffers. One obvious thing to try the nocache command before your copy, so at least the input file is not buffered. – ubfan1 Oct 03 '24 at 16:06
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    @ubfan1 - While there may be a few ways to get better performance, the question here is why the difference between Ubuntu 22.04 and 24.04 given all other factors are the same. To me, that suggests something changed in Ubuntu 24.04 and not for the better. Of even more concern is what will Ubuntu 26.04 performance look like. – quill Oct 03 '24 at 19:41
  • Up to a point, using more buffers is good, improving perceived performance. The dirty-bytes and dirty-bytes-ratio may be a way to tweak the aggressiveness of buffer use. – ubfan1 Oct 03 '24 at 20:24
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    Changing dirty_bytes and dirty_bytes_ratio only caused the copying process to flush data to the USB drive earlier. Overall, the copying performance on 24.04 is terrible. When transferring data to a USB 3.0 drive, I notice the speed drops from 20 MB/s to 10 MB/s, and sometimes even down to 3 MB/s. The port is also USB 3.0. – ENIAC Oct 19 '24 at 15:33

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