Description

This article explains the behavior of percentage shown under "show system storage" for /dev/ad0s1a filesystem

Symptoms

You may see /dev/ad0s1a near 100%, for example 98% for some Junos sometimes

Solution

Partition /dev/ad0s1a is compact flash memory.(CompactFlash Card).

It's size utilization goes according to the size of the packages installed on the device. When running 'show system storage', it is expected to have 98% for version 20.4 or above.

Tested in the lab.

<Example1>
******************
{master:0}
root@r113> show system storage 
fpc0:
--------------------------------------------------------------------------
Filesystem    Size  Used  Avail Capacity Mounted on
/dev/ad0s1a    1.4G  1.3G  24M  98% /

******************

<Example2>
******************
root@r024> show system storage
fpc0:
--------------------------------------------------------------------------
Filesystem    Size  Used  Avail Capacity Mounted on
/dev/ad0s1a    1.4G  1.3G  24M  98% /

******************


This size will NOT change with zeroize per the lab test.

<Before zeroize>
***********************
{master:0}[edit]
root@r024# run show system storage
fpc0:
--------------------------------------------------------------------------
Filesystem    Size  Used  Avail Capacity Mounted on
/dev/ad0s1a    1.4G  1.3G  24M  98% /

-snip-

***********************


<After zeroize>
***********************
{master:0}[edit]
root# run show system storage
fpc0:
--------------------------------------------------------------------------
Filesystem    Size  Used  Avail Capacity Mounted on
/dev/ad0s1a    1.4G  1.3G  24M  98% /

-snip-

***********************


To reinforce, partition /dev/ad0s1a is compact flash memory, which size varies according to the size of the packages installed on the device and this could differ between different Junos versions. HIgh percentaje of utilization on here is not an issue and should not cause any problem.

Modification History

2023.8.30 Ver1
2025.10.30 Ver2