Bad read-speed on RaspPi (but good write)

  • Hello everyone,

    Maybe you can help me with my problem, all the other contributions I have found so far in the vastness of the Internet have not been able to solve the problem.

    A small spoiler in advance:

    The text is translated with "", (not sponsored ;)) I think that makes it a bit more understandable than if I try it myself.

    Answers in English are of course no problem.

    I have a Raspberry Pi 4 with OMV installed. A 2.5" HDD is connected. Sharing in the home network via SMB. The entire home network is designed for 1Gbit/s, including switches, cabling and network cards.

    The write speeds also match: From Windows 10 -> RPi-OMV = ~110 MB/s.

    Unfortunately, the read speeds are much lower: From RPi-OMV -> Windows 10 (SSD) = 35-55 MB/s.

    I tried the transfer with different end devices, also under Linux. The values were always nearly the same.

    I don't understand why the transfer from the NAS to Windows/Linux is so much slower than the other way round. Actually, it reads from the NAS HDD, which in my opinion should be faster than writing.

    I will list more technical data below and also what I have already tried.

    I hope I can still get everything together so far...


    Raspberry Pi 4 Model B Rev 1.5

    Original Manufacturer power supply

    OS: Raspbian lite (64bit)

    Linux version: 5.15.32-v8+

    OMV version: 6.0.21-1 (Shaitan)



    OS (MicroSD): 64GB SanDisk Extreme

    Data (HDD): 2.5" / USB 3.0 / 4TB / XFS / write cache enabled


    I have also tested with an external USB 3.0 3.5" HDD with external power supply, here I achieve a read speed of ~60MB/s.

    I have tested all extras in the SMB settings and shares as far as I know, but this has not helped.

    I have attached a screenshot of the share.

    I also ran "$ sudo hdparm -t /dev/sda1". The results are exactly as I would like them to be:


    Timing buffered disk reads: 356 MB in 3.01 seconds = 118.22 MB/sec.

    I must have forgotten some important info, please let me know.

    Greetings from Germany, I am grateful for any help.

  • contributions I have found so far in the vastness of the Internet have not been able to solve the problem.

    I'd recommend to search specifically in this forum using "".

    There are many similar reports of bad performance with 2.5'' HDDs.

    From my view it could be caused by Shingled magnetic Recording (SMR) and a too small drive hardware cache in combination with "XFS / write cache enabled".

    Is your 2.5'' HDD one of these…ols=959&fcols=8457&sort=p ?

    does performance change when HDD write cache is disabled?

    omv 6.0.28-3 (Shaitan) on RPi CM4/4GB with 64bit Kernel 5.15.32-v8+

    2x 6TB 3.5'' HDDs (CMR) formatted with ext4 via 2port PCIe SATA card with ASM1061R chipset providing hardware supported RAID1

    omv 5.6.21-1 (usul) on RPi4/4GB with 32bit Kernel 5.10.63 and WittyPi 3 V2 RTC HAT

    2x 3TB 3.5'' HDDs (CMR) formatted with ext4 in Icy Box IB-RD3662-C31 / hardware supported RAID1

    For Read/Write performance of SMB shares hosted on this hardware see forum here

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