Extremely slow speed when writing to USB FAT32 drive in Linux

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I'm trying to copy around 4GB of files onto a USB 3.0 drive formatted with FAT32. The speed is ridiculously slow - 200 kBytes/sec. Writing data directly with dd is okay at about 25-30 MBytes/sec, and writing the same data on an ext4 partition on the same device is going at 9-10MBytes/sec. I am running Arch Linux at 4.1.2 kernel. Any ideas on what's going on?

John Ashpool

Posted 2015-09-09T15:54:41.533

Reputation: 189

Answers

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The problem, as it turns out, was the sync option used to mount the filesystem, which appears to be performance-killer. Mounting it with flush option instead of sync solved the problem: sudo mount -o async,flush <device> <mountpoint>

John Ashpool

Posted 2015-09-09T15:54:41.533

Reputation: 189

you are my hero – Nicolas Holthaus – 2017-11-03T13:22:31.053

By the way, how did you figure out that sync option was the performance-killer ? – onurcanbektas – 2019-08-22T05:49:10.283

Asked: 2015-09-09T15:54:41.533

Viewed: 7 236 times

Active: 2015-09-11T18:19:16.360