Arch Linux

Whaleyy

Member

Registered: 2021-12-25

Posts: 15

USB File Copy Super Slow and Stuck

I've been looking through different posts for a solution to this matter, but none of them seems to work. For example, adjusting

dirty_background_bytes

and

dirty_bytes

didn't have an effect, it just slows down the process even more.

Screenshot: https://imgur.com/a/pG5u2x1

As you can see, I am trying to transfer files from Windows ISO to my USB stick. The drive has been formatted to NTFS. The speed was fast at first and then it just kinda hangs at a certain value in GB range. Is there any workarounds for this? I read somewhere about setting MM to "Never", by default, mine's already been set to "Never".

Some details of "vm.dirty"

vm.dirty_background_bytes = 0
vm.dirty_background_ratio = 10
vm.dirty_bytes = 0
vm.dirty_expire_centisecs = 3000
vm.dirty_ratio = 20
vm.dirty_writeback_centisecs = 500
vm.dirtytime_expire_seconds = 43200

Last edited by Whaleyy (2022-01-16 04:47:39)

seth

Member

Registered: 2012-09-03

Posts: 51,319

Re: USB File Copy Super Slow and Stuck

The usb key is slow and possibly there're IO errors (check the dmesg!)

The fast initial progress is the fast source being read into the RAM cache - once that's saturated and has to be synced to the actual target device, you're facing the limitations of the target device.
Efforts to make the operation more synchronous by limiting the cache or actually forcing a sync mount that circumvents the cache altogether will just increase the total duration.

On a filesystem level, the ntfs-3g userspace driver isn't very fast, the recently added ntfs3 driver should™ perform better.

But that doesn't change anything about the fundamental "problem" of async data transfer from a fast source to a slow target and GUI indicators having a hard time with that. To accurately reflect the writing, they'd have to inspect the target file size all the time, what again would slow down the process.
What they could probably do would be to notice that the progress has just stalled drastically and figure "'key, this is probably the real speed and everything else was cache, so reset the indicator" but that produces errors when dealing w/ variable speed destinations (network or some bad sectors on the target drive)

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