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  • 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.
  • I had problems with a UGREEN SATA to USB adapter myself, and my SSD would randomly disconnect and cause my system to crash. It worked fine for around a year before failing. I fixed this by buying a different adapter. – user96931 Apr 3 at 1:33
  • Problem with blaming the adaptor is that when using it with my windows pc I get decent write speed. – sprocket12 Apr 4 at 1:48
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Check if you have UAS errors: some USB3 storage devices perform better if you disable UAS and use them as a good old mass storage.

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.

| improve this answer | |
  • iperf shows 907 Mbit connection. I disabled UAS it was still the same, then I added a dedicated power supply to the adapter (it has a socket for it) and still I only get 32 MBytes/s. Not sure what is left. Btw its a HDD / Gen 1 SATA I believe not an SSD – sprocket12 Apr 2 at 14:21
  • The read speed I get is ~ 82MBytes/s which is decent. – sprocket12 Apr 2 at 14:42
  • @sprocket12 What is about the CPU load? – Dmitry Grigoryev Apr 3 at 0:08
  • Not sure how to check the CPU load, the top command definitely shows sys going above 0.2 during transfer, but that may be normal. – sprocket12 Apr 4 at 1:47

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