Alright, I need to classify this bug report as either 'user-mode' or 'system-mode'. Let me think through the details. The issue is about qemu-nbd failing to discard bigger chunks of data when using a block device. The user provided some commands showing that when they create a small image (2M), blkdiscard works fine, but it fails with a larger image (5G). Qemu-nbd runs in user space, right? So it's a user-mode application that connects to a QEMU virtual machine. However, the problem here involves block device operations which are typically handled by system services and kernel components. Looking at the report, the issue is related to how the nbd device handles discard commands for larger chunks. The /sys/block/nbd0/queue/discard_max_bytes file suggests it's a sysfs entry, which is part of the Linux kernel. When blkdiscard is called on /dev/nbd0, it's interacting with the kernel's block layer. So even though qemu-nbd is user-mode, the problem arises when dealing with device-specific operations that are managed by the system (kernel). The failure in discarding larger chunks points to how the nbd driver or the underlying storage handles these requests at a lower level. Therefore, this issue is likely related to system-mode components because it involves kernel-level block device handling and possibly driver interactions. system