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Error: usb (/dev/da0) media missing or invalid on ACX5000

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Article ID: KB31541 KB Last Updated: 30 Mar 2017Version: 1.0
Summary:

Due to the absence of NAND flash on the ACX5000 series routers, the command, 'request system snapshot slice alternate' will look to copy the active partitions to the USB.
If the USB ports are empty, then the command will fail and return an error.

Symptoms:

On ACX5048 or ACX5096, the command 'request system snapshot slice alternate' returns the following error:

{master:0}
lab@R1> request system snapshot slice alternate
fpc0:
------------------------------------------------
error: usb (/dev/da0) media missing or invalid

Cause:

The ACX5000 series devices do not have a NAND flash built-in to the routing engine.

The following command shows that there is no NAND flash on the ACX5048 router:

{master:0}
lab@R1> show chassis hardware detail
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                WC3715300006      ACX5096
Pseudo CB 0
Routing Engine 0          BUILTIN      BUILTIN           ACX5K Routing Engine
  ad0     509 MB  QEMU HARDDISK        QM00001           Hard Disk
  ad1    4095 MB  QEMU HARDDISK        QM00002           Hard Disk
  ad2     511 MB  QEMU HARDDISK        QM00003           Hard Disk
  ad3    1023 MB  QEMU HARDDISK        QM00004           Hard Disk
  usb0 (addr 1)  product 0x0000 0      vendor 0x0000     uhub1
  usb0 (addr 2)  product 0x0020 32     vendor 0x8087     uhub2

Output from ACX2000 series router, that shows NAND flash is built-in to the routing-engine:

lab@R1> show chassis hardware detail
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                HS0212511608      ACX2000
Midplane         REV 12   650-037055   HS0212511608      ACX2000
Routing Engine            BUILTIN      BUILTIN           Routing Engine
  da0    3820 MB  USB DISK 2.0                           Nand Flash 0
FEB 0                     BUILTIN      BUILTIN           Forwarding Engine Processor

The command, 'request system snapshot slice alternate' by default, looks for a NAND flash to copy the running configuration and Junos:

lab@R1> request system snapshot slice alternate
Doing the initial labeling...
Verifying compatibility of destination media partitions...
Running newfs (439MB) on internal media  / partition (da0s2a)...
Running newfs (46MB) on internal media  /config partition (da0s2e)...
Copying '/dev/da0s1a' to '/dev/da0s2a' .. (this may take a few minutes)
Copying '/dev/da0s1e' to '/dev/da0s2e' .. (this may take a few minutes)
The following filesystems were archived: / /config

As seen above, active partitions are copied to the internal media, which is da0 (nand flash).

Solution:

Due to the absence of NAND flash on the ACX5000 series routers, the command, 'request system snapshot slice alternate' will look to copy the active partitions to the USB.
If the USB ports are empty then the command will fail resulting in the following error message

{master:0}
lab@R1> request system snapshot slice alternate
fpc0:
-----------------------------------------------
error: usb (/dev/da0) media missing or invalid

To solve this issue, a USB must be inserted into one of the 2 USB ports so that the active partitions are copied to the USB.

The following output shows a USB inserted into one of the 2 USB slots:

{master:0}
lab@R1> #umass0: Unigen Corporation PQS4000B8-JNP, rev 2.00/11.00, addr 3
inserted USB
Mar 02 11:02:43

{master:0}
lab@R1> da0 at umass-sim0 bus 0 target 0 lun 0
da0: <Unigen PQS4000 1100> Removable Direct Access SCSI-0 device
da0: 40.000MB/s transfers
da0: 3824MB (7831552 512 byte sectors: 255H 63S/T 487C)

Now, when the command is executed, it does not return the error message and the active partitions are successfully copied to the USB as shown below:

{master:0}
lab@R1> request system snapshot slice alternate
fpc0:
------------------------------------------------------------------------ --
Starting snapshot to usb (/dev/da0)
Creating snapshot on the host ..
umass0: at uhub2 port 2 (addr 3) disconnected
(da0:umass-sim0:0:0:0): lost device
(da0:umass-sim0:0:0:0): removing device entry
umass0: detached
Copying bootable disk image from host ..

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