Avamar NDMP browsing Isilon shows an incorrect directory structure

When using Avamar UI to browse the Isilon directory structure, after the user initiates a browse and expands the subfolders, some directories appear in a nested loop structure. However, when checking the same directories using the Isilon web UI or CLI, the subfolders are located at the same level, with no nested loop structure observed.

When browsing Isilon directories on Avamar, user authentication is required. Isilon supports two authentication methods. The original method is 'basic authentication'.

A new method, 'session-based authentication', was introduced and enabled by default starting with Isilon OneFS 9.2 to enhance security. However, the Avamar NDMP browse method was not updated to accommodate this change, which is why this issue was not observed in earlier versions like OneFS 9.1.

When 'session-based authentication' is enabled and the number of subfolders exceeds 150, it triggers a browse path calculation issue in the ctl_message between the avndmp and avtar processes on the NDMP Accelerator node.

This is identified as a issue and will be fixed in future releases.

Workaround

Step 1: On Isilon 9.2 and onward versions, we can enable 'basic authentication' by this command in the Isilon CLI:

isi_gconfig -t web-config auth_basic

Step 2: After 'basic authentication' is enabled, add this flag into /usr/local/avamar/var/<Isilon_node>/avndmp.cmd

--enable-session-based-authentication=false

Note: This workaround would decrease the security, customers must evaluate it before applying it. This is acceptable when both the Isilon and Avamar nodes are used in a private and well-secured environment.

If this is not acceptable for security reasons, customers can also consider the following:

1. Avoid creating too many subfolders in the same directory
2. Temporarily ignore the looped directories and wait for the new NDMP software release. This issue does not impact general NDMP backup/restore jobs

See AVAMARESC-2114 to read more details about this issue.