So I'm still experimenting issues with an external HDD on Linux and was hoping someone could help me out. Basically, I have a toshiba external HDD that in both NTFS or ext4 copies very slowly like 5mb/s, but if I use it in a Windows OS it copies normally (average 100mb/s). I've tried several ways of formatting in gparted and can't find a decent solution. When I start transferring files to my ext hdd basically it starts at 100mb/s but slowly decreases until it reaches like 5mb/s.

@ringu Hmm, no ideas myself but I boosted in case someone else does!

@le_ArthurDent This does not justify transfer being as slow; given the large amount of data (over 200gb) I hate to transfer this speed is not feasible.

No it doesn't. I am not a hard drive expert. Maybe GPT partition table brings some advantage? Or maybe your drive is heavily fragmentent.

@le_ArthurDent Tried that already and no difference. This is odd specifically because this is my newest ext HDD and my oldest which is a lot slower on Windows works perfectly fine on Linux.

Have you explored if the issue has to do with the port/s of connections?

@mrojo I have tried to use different USB ports with no discernible difference

@ringu Anything in the logs maybe that could give more insight?


@ringu Of course not! 😉️ Just do a `tail -f /var/log/messages` while plugging your hdd and copying the data. If you see error messages related to IO or USB, then there is a problem.


@brejoc @mrojo

I'm afraid I don't have any file named messages in /var/log however I do have a syslog and

@ringu @brejoc @mrojo
1. Your disk may have physical sectors bigger than 512 bytes, and the specific controller in the disc case collides with linux driver. You could try putting the toshiba hdd into one of the fast cases.

@rudolf @brejoc @mrojo

Do you mean putting my toshiba external into a different case?

@ringu @brejoc @mrojo Taking the Toshiba disk out of the Toshiba case and putting it into another case. You might need to try more than one (more) case.

@rudolf @brejoc @mrojo

This is gonna be a bit troublesome because this disk is on a factory case with tiny screws but I might try that. My other disks are all in cases I bought so it's easier to switch.

@rudolf @brejoc @mrojo

Relevant update but when I transfer files from my ext disc to my PC it transfers fine, the issue only persists when transferring from my PC to the ext disc.

@ringu @brejoc @mrojo That is exvactly where the big sectors cause problems.

Blocksize? Newer hard drives are optimized for larger blocksizes. You need to set the correct blocksize while formatting the partition.

Other possibility: check whether the correct kernel modules are loaded when you hook up the USB disk: xhci VS ehci.

@ringu You could try setting sysctl values vm.dirty_ratio and vm.dirty_background_ratio to a smaller value.

Are you sure it's not reporting the cache speed initally? Sometimes dd tool claims to have copied 2gb in 10seconds but 2minutes passes after I type 'sync'. Best approach is to record the time taken to safely copy the whole file.

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