Cisco – persistent-data file in nvram root on Cisco switches

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Does anyone know what this is? Can't read it or delete it, both del and erase nvram do not appear to work on it. I am erasing switches and need to confirm that it does not contain sensitive information.

The name of the file is "persistent-data". It is located at "nvram: persistent-data". It appears when running the latest IOS release for the Cisco 2821 as well as IOS XE.

Will edit post to show output and the additional models of switch I have spotted it on soon.

Best Answer

The router’s NVRAM used to contain the startup configuration file only, but this is no longer strictly the case. Recent IOS releases also use the same NVRAM space to store information such as private keys for SSH or IPSec (private-config), and interface numbers for SNMP (ifIndex-table).

Router1#dir nvram: 
Directory of nvram:/

   20  -rw-        5068              <no date>  startup-config
   21  ----        2302              <no date>  private-config
    1  ----           0              <no date>  persistent-data
    2  -rw-         133              <no date>  ifIndex-table

You cannot delete nor read these two files as they strictly belong to the IOS system on your switch or router. Those files do not contain anything sensitive. It is strictly system information that has no relation to any configuration.

Update: OK so i've been searching all over for this and i found this thread:

https://supportforums.cisco.com/t5/borderless-networks/what-is-quot-persistent-media-ifs-general-error-quot/td-p/2402199

There's an error generating the following message:

%PRST_IFS-3-GENERAL: persistent media IFS general error: Open Read - can't open  nvram:persistent-data errno is 16

Searching for this lead me to believe that the Cisco IOS File System (IFS) saves some persistent date (variables) about the Cisco image in the NVRAM. This data is used upon booting the switch or router.

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