This article suggests a workaround when users are unable to mount a USB device on QFX devices due to the QFX device not recognizing the USB.

Unable to mount a USB device on QFX5210. The following errors are seen when the USB device is plugged in:

root> sd 6:0:0:0: [sdb] No Caching mode page found
sd 6:0:0:0: [sdb] Assuming drive cache: write through
sd 6:0:0:0: [sdb] No Caching mode page found
sd 6:0:0:0: [sdb] Assuming drive cache: write through
sd 6:0:0:0: [sdb] No Caching mode page found
sd 6:0:0:0: [sdb] Assuming drive cache: write through

To work around the issue, perform the following steps:

1. Go to the Linux host shell:

root> request app-engine host-shell  (This will require root password.)

2. At the host shell prompt, enter the following command:

lspci -nn | grep USB | cut -d '[' -f3 | cut -d ']' -f1 | xargs -I@ setpci -H1 -d @ d0.l=0

3. Following this, the USB device will be properly mounted to dev/da* .

ugen1.4: <General USB Flash Disk> at usbus1
umass0 on uhub3
umass0: <General USB Flash Disk, class 0/0, rev 2.00/1.00, addr 4> on usbus1
da0 at umass-sim0 bus 0 scbus2 target 0 lun 0
da0: <General USB Flash Disk 1.00> Removable Direct Access SPC-2 SCSI device
da0: Serial Number 04756B00000067EA
da0: 40.000MB/s transfers
da0: 7667MB (15702112 512 byte sectors)
da0: quirks=0x2<NO_6_BYTE>