I'm using Samba Server 4.8.0 on Asus N56U router (Linux kernel: 3.4.113). An external 2TB USB hard drive is used as the file share drive, it's formatted into ext4.

So far everything is working perfectly except one thing: any files larger than 2GB are not showing up on SMB clients (no matter it's Linux or Windows).

I searched on internet, it seems most of the issues are related not being able to copy or write files larger than 2GB. But my issue is that the large files simply won't show up.

Any thoughts about the possible cause here? Thanks!

What file system in on the USB Drive? Some older files systems, particular older FAT systems, have file size limits.

https://www.genie9.com/support/kb/Kn....aspx?KBID=113

I can't find any hard evidence but it might the router is only running SMB version 1.0 which could of had those limitation. Can you copy large files to the router.

Thanks for the input. I did some more testing and found below:

The hard drive is formatted in ext4 format. I tried to read/write files larger than 2GB on the USB hard drive, it was working. I also tried to use vsftpd to share files on the same hard drive, it works fine too with files larger than 2GB.

One thing interesting is that I tried Samba (ver 3.6.25), files larger than 2GB are working fine. However, I could not use SMB3.0 on it, that was the reason I used Samba 4.8.0.

Different SMB versions (SMB 1.0/2.0/3.02/3.11) were also attempted to connect to Samba 4.8.0, all had the same result (large files doesn't show, and copy large files to share fail). From the smbd debug logging, it appears the input offset will become negative after 2GB mark when copying a large file to the share.

------- excerpt of output --------------
smbd_smb2_write: Downloads/2gb - fnum 2357515247
smb2: write size (1048576) too small for minimum aio_write of 0
real_write_file (Downloads/2gb): pos = -2118123520, size = 1048576, returned -1
smb2_write failed: fnum 2357515247, file Downloads/2gb, length=1048576 offset=0 nwritten=-1: NT_STATUS_INVALID_PARAMETER
smb2: write on file Downloads/2gb, offset 2176843776, requested 1048576, written = 4294967295
smbd_smb2_request_error_ex: smbd_smb2_request_error_ex: idx[1] status[NT_STATUS_INVALID_PARAMETER] || at ../source3/smbd/smb2_write.c:135
smbd_smb2_request_done_ex: idx[1] status[NT_STATUS_INVALID_PARAMETER] body[8] dyn[yes:1] at ../source3/smbd/smb2_server.c:3200
smb2_set_operation_credit: requested 16, charge 16, granted 16, current possible/max 16/512, total granted/max/low/range 512/8192/33267/512