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I've just bought a Toshiba Canvio Advance 1TB external hard drive that connects to a USB 3.0 port. I've formatted it with file system ext4 using Ubuntu's Disks utility. When I take a full backup of my laptop's hard disk, the transfer rate starts very fast, something around 300 MB/s, but it quickly slows down to 30 MB/s as its "steady" rate. Why is that happening? Shall I upgrade the USB driver? My laptop has 16 GB of RAM and is running Ubuntu 22.04. Thanks.

user2083893
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  • Search this site for slow copy Lots of problems like yours, Shingled Magnetic Recording used on the disk really slows things down even more, disk buffer used to make the initial part of copy seem fast, system buffers fill up and the whole system slows to a crawl...See https://askubuntu.com/questions/995946/decrease-of-transfer-rate-when-copying-large-amount-of-data Basic problem is write is slower than read, buffers fill up, and things slow down. Many approaches to making reads better match writes to avoid dragging system down. – ubfan1 Feb 04 '23 at 04:11
  • Thanks for your input. My external HDD being a thin 1TB, it certainly doesn't use Shingled Magnetic Recording! – user2083893 Feb 05 '23 at 05:13
  • Ok, I believe you, it's just that Wikipedia says SMR is normally for 4TB+ hard disks. Anyway, I've found from a previous post the following tweaks: – user2083893 Feb 07 '23 at 02:59
  • echo $((16*1024*1024)) > /proc/sys/vm/dirty_background_bytes – user2083893 Feb 07 '23 at 03:03
  • echo $((48*1024*1024)) > /proc/sys/vm/dirty_bytes – user2083893 Feb 07 '23 at 03:03
  • The copy to the USB 3.0 drive still slows down, but to a steady rate of about 70 MB/s, which is sufficient for my needs. Thanks everybody! – user2083893 Feb 07 '23 at 03:03

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