raspberry pi 4 with usb 3 adapter to sata harddrive write slower than usual

Question

• I have a 2.5 inch SATA HDD hooked up to a UGREEN USB 3 to SATA connector.
• The HDD is formatted as NTFS.
• On my Windows PC I get write speeds of about 80 MBytes/s.
• I am running OMV on the Pi 4.
• On Raspberry Pi 4 4GB on the USB 3 slow over gigabit LAN as a SMB share I get 34 MBytes/s max.

Why is this? What could be the bottleneck?

Startup log:

[    0.493412] of_cfs_init
[    0.493507] of_cfs_init: OK
[    0.494102] Waiting for root device PARTUUID=738a4d67-02...
[    0.540285] random: fast init done
[    0.593604] mmc0: new ultra high speed DDR50 SDHC card at address aaaa
[    0.594126] mmc1: new high speed SDIO card at address 0001
[    0.595505] mmcblk0: mmc0:aaaa SL08G 7.40 GiB
[    0.596907]  mmcblk0: p1 p2
[    0.615685] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. O                                                                         pts: (null)
[    0.615755] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
[    0.620316] devtmpfs: mounted
[    0.627977] Freeing unused kernel memory: 2048K
[    0.668531] Run /sbin/init as init process
[    0.758323] usb 1-1: new high-speed USB device number 2 using xhci_hcd
[    0.940957] usb 1-1: New USB device found, idVendor=2109, idProduct=3431, bcd                                                                         Device= 4.21
[    0.940997] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[    0.941023] usb 1-1: Product: USB2.0 Hub
[    0.942790] hub 1-1:1.0: USB hub found
[    0.943127] hub 1-1:1.0: 4 ports detected
[    1.081126] systemd[1]: System time before build time, advancing clock.
[    1.088731] usb 2-1: new SuperSpeed Gen 1 USB device number 2 using xhci_hcd
[    1.119705] usb 2-1: New USB device found, idVendor=174c, idProduct=55aa, bcd                                                                         Device= 1.00
[    1.119743] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[    1.119771] usb 2-1: Product: AS2115
[    1.119794] usb 2-1: Manufacturer: ASMedia
[    1.119817] usb 2-1: SerialNumber: 12345678984B
[    1.122847] usb 2-1: UAS is blacklisted for this device, using usb-storage in                                                                         stead
[    1.123000] usb 2-1: UAS is blacklisted for this device, using usb-storage in                                                                         stead
[    1.123033] usb-storage 2-1:1.0: USB Mass Storage device detected
[    1.123478] usb-storage 2-1:1.0: Quirks match for vid 174c pid 55aa: c00000
[    1.123625] scsi host0: usb-storage 2-1:1.0
[    1.175708] NET: Registered protocol family 10
[    1.176927] Segment Routing with IPv6
[    1.207978] systemd[1]: systemd 241 running in system mode. (+PAM +AUDIT +SEL                                                                         INUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +                                                                         XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybr                                                                         id)
[    1.208855] systemd[1]: Detected architecture arm.

Answer 1

Check if you have UAS errors (e.g. sudo dmegs | grep uas): some USB3 storage devices perform better if you disable UAS and use them as good old mass storage. To do so, edit /boot/cmdline.txt and add the text usb-storage.quirks=<VID>:<PID>:u (idVendor / idProduct of the USB device in question) to the kernel command line.

If not, find out where the bottleneck comes from: storage, CPU or network. CPU can be ruled out by watching system load during a write (should be 20% or less). Network can be tested by piping data to /dev/null (you should be able to reach 80 MB/s there). Otherwise it's the combination of Raspberry / SATA adapter / SSD which is slow.