When reading optical media, dmesg shows a message like one of the following:

[  115.013295] blk_update_request: I/O error, dev sr0, sector 343608 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0


[   49.763459] blk_update_request: I/O error, dev sr0, sector 342768 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0

Sometimes I'm able to read a ton of bytes, sometimes I'm not. After this happens whatever operation I try to do on the drive including eject just hangs. Any idea what's going on? The status LED for the SATA to USB cable becomes solid at this point. I can still see /dev/sr0, but if I run echo 1 > /sys/block/sr0/device/delete; echo "- - -" > /sys/class/scsi_host/host0/scan it doesn't come back.
I am supplying the drive with external power, so it's not being powered off of the 500mA of the Raspberry Pi. It's not making funny sounds that would be indicative of insufficient power when reading either.

Edit: it seems to work fine when I plug the power cable directly into a laptop, but if I put it through I microUSB to USB adapter it fails, could the adapter be giving enough resistence to go from enough power to not-enough power?

  • At some point your description is strange. You say that you use an external power supply. But later you write about using a notebook as power source which clearly indicates that the USB drive is powered via USB. So taking both into account the external power cable is USB? Does this mean the USB CD drive has two USB cables, one for power and one for data or is it just an ordinary (illegal) Y- cable? If it is a Y cable it is not designed to be connected to two different power sources. Use an external powered USB hub.
    – Robert
    Nov 5, 2021 at 21:34
  • What I'm saying is that the DVD drive has two USB cables yes, one for data and one for power
    – 0x777C
    Nov 6, 2021 at 17:27

1 Answer 1


External CD/DVD drives are known for being power-hungry. It is often difficult to get them to work reliably from an USB power source. So yes, I would absolutely say that a small adapter can make the difference between a working drive and a failing one. Other factors may contribute, too: Length and quality of power cable, type and current rating of power supply, etc. What does the vendor recommend for this drive?

  • It's an internal drive, I'm just using adapters to make it work with the Raspberry Pi
    – 0x777C
    Nov 6, 2021 at 17:28
  • That's an unusual combination, an internal drive with two USB connectors. Normally, these would have an SATA connector. Does it have another connector as well (such as a round power-supply connector or a drive power connector)?
    – PMF
    Nov 7, 2021 at 7:22
  • The internal drive has a mini SATA connector, which I'm connecting to an adapter which provides split USB
    – 0x777C
    Nov 7, 2021 at 15:39

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