Package: util-linux Version: 2.38.1-5+b1 Severity: normal Tags: upstream Many devices has maximum discard size, DISC-MAX in `lsblk --discard` output. However, blkdiscard by default is doing full-device discard, which is also specified in its manual page. This results in errors and some drivers turning discard support off. For example:
# cat /sys/devices/pci0000:00/0000:00:02.1/0000:01:00.0/usb2/2-4/2-4:1.0/host6/target6:0:0/6:0:0:0/scsi_disk/6:0:0:0/provisioning_mode unmap # lsblk --discard NAME DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO sda 0 512B 4G 0 # blkdiscard -f -l 4G /dev/sda blkdiscard: Operation forced, data will be lost! #### this works # blkdiscard -f -l 5G /dev/sda blkdiscard: /dev/sda: BLKDISCARD ioctl failed: Remote I/O error # cat /sys/devices/pci0000:00/0000:00:02.1/0000:01:00.0/usb2/2-4/2-4:1.0/host6/target6:0:0/6:0:0:0/scsi_disk/6:0:0:0/provisioning_mode disabled Kernel log: [217264.437619] sd 6:0:0:0: [sda] tag#8 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s [217264.437632] sd 6:0:0:0: [sda] tag#8 Sense Key : Illegal Request [current] [217264.437638] sd 6:0:0:0: [sda] tag#8 Add. Sense: Invalid field in cdb [217264.437645] sd 6:0:0:0: [sda] tag#8 CDB: Unmap/Read sub-channel 42 00 00 00 00 00 00 00 18 00 [217264.437648] critical target error, dev sda, sector 134217728 op 0x3:(DISCARD) flags 0x4000 phys_seg 1 prio class 2 Having said this, I'm not really sure who's in charge here. Maybe it is the kernel driver who should split the large request into smaller parts. But the end result is that whole thing stops working (and some devices even fall off the usb bus and needs to be re-set). And for quite some times I was sure discard/trim is not supported on USB-connected devices at all, just because this quick blkdiscard test always fails like this, - and I thought it is the command which is illegal, not its parameter.
