Trying to copy large files to External Drive connected to TO. Failed

Hello again community,

Found another interesting quirk with my TO. Here’s the details:

  • Was trying to copy some ISO’s to the USB drive connected to the rear USB 3.0 port on my TO (its a 128 GB Lexar). It would only copy at 15-20 MB/s even though the USB drive is capable of 150 MB/s, but i’m not going to complain about that right now:).

  • The ISO’s were between 4.5 and 8 GB’s respectively. I’m doing this in anticipation of being able to image computers over my network with TFTP or using it as some network accessible storage right from the router (maybe). Honestly i’m just playing around.

The problem

When copying the files, it seems to hit a hard limit of 4,194,304 KB. Here’s the exact error message i get when trying to copy files with WinSCP:

General failure (server should provide error description).
Error code: 4
Error message from server: Failure

Common reasons for the Error code 4 are:

  • Renaming a file to a name of already existing file.
  • Creating a directory that already exists.
  • Moving a remote file to a different filesystem (HDD).
  • Uploading a file to a full filesystem (HDD).
  • Exceeding a user disk quota.

Is this due to the file system on the external drive? I’m not completely convinced but i could always reformat to something else if thats really the reason…but i don’t think it is somehow.

Thank you everyone for your help!

Which filesystem do you have on the Lexar?

@davey it’s FAT32 file system

In that case it ought to be the 4GB limit in the fat32 system that puts a stop to it.

A reformat to another file system will solve the large file copying. :slight_smile:


Thanks Mr. Davey. I’ll give that a shot.

@davey finally got around to reformatting to EXT4 (as i figured that would be the most acceptable file system) and you were/are quite right. After I did that, it accepted both files.

Any suggestions on a better file system? I ask because formating as EXT4 caused me to lose more available disk space than FAT32

Also, does anyone know why copying is so slow? I’m only getting 15 MB/s and i’m wondering if thats the norm. I’m copying through winSCP.

Thank you

How much space does ext4 give you? 119GiB is the maximum possible for this size of usb stick for any filesystem. Some manufacturers even have lower values. I would say 115GiB is an expected value.

If write speed is not advertised on the package then 15MB/s may be the maximum of this stick. I won’t expect more than 30 MB/s from any normal USB3 storage stick anywhere.

Copying from WinSCP will be limited to around 50MB/s because the encryption can’t be much faster.

@adminX it gives me 111.75 GB. Feels a bit far from 119 but I won’t be a baby about it :).

You’re right! IT offers reads speeds up to 150MB/s and write speeds up to 45MB/s for quick access and transfer of your data.

Good to know winscp is limited to 50mb/s. Is there a faster route I could explore to copy files, so I could compare and contrast?

All filesystems need space for metadata like filenames, file attributes and internal disk layout. It varies how much filesystems preallocate space for metadata but all filesystems need space for it. It is normal for filesystems to use 5-10% of the total capacity for metadata.

Fair enough. Thanks Mr. @white