Fixing AIX Veeam agent job startup delay issue

This week, I encountered an issue with AIX agent backups. I have several AIX servers running versions 7.2 and 7.3. The backup jobs start, but there’s a significant delay before they actually begin. When they start at all. Therefore, in this article, we shall discuss the steps to Fixing AIX Veeam agent job startup delay issue. Please, see the steps to Fix missing path and delete a Veeam Backup Repository, and how to Backup Mac with Veeam Agent for Mac to Synology DS923+ NAS.

When they do, the throughput is extremely low, and some jobs run for over 20 hours. The most severe issues seem to occur on AIX 7.3.

Also, see “Why you should not use Public DNS in Production: Change DNS Server in Windows“, and how to “Force immediate MBAM Encryption: Why does the MBAM Agent delay most times in encrypting devices“.

Troubleshooting steps

To troubleshoot, I tried:

• Uninstalling and reinstalling the Veeam Agent
• Creating a new protection group to ensure fresh package deployment and a new XML file

However, the issue persists. When the job starts, it returns the path to the log file, and upon reviewing the logs, I found that “Path”.

/var/log/veeam/Backup/JOB-Backup/Session_20250402_160020_\{311f3273-44bf-476e-93ab-7e8f9a943b07\}/Agent.Source.log

Below is the log output

[02.04.2025 16:02:46.438] <53084711> fb | Estimation:
[02.04.2025 16:02:46.438] <53084711> fb | Backup stats:
[02.04.2025 16:02:46.438] <53084711> fb | Total counts: files [607165], dirs [60021], links[9595], hard_links[3583]
[02.04.2025 16:02:46.438] <53084711> fb | Sizes: total files size
[271919853250], max file size [40719097856], aver. file size [447851.660175], total dirs size [676930], max dir size [21859], aver. dir size [11.278219]
[02.04.2025 16:02:46.438] <53084711> fb | Files distribution: <1Kb [325475], 1-20Kb [230080], 20-50Kb [22112], 50-200Kb [16239], 200Kb-1Mb [8243], 1-100Mb [4717], 100Mb-1Gb [269], >1Gb [30] [02.04.2025 16:02:46.438] <53084711> fb | Dirs distribution: <10 [50076], 10-100 [9217], 100-1000 [701], 1000-10000 [25], >10000 [2]
[02.04.2025 16:03:16.777] <39977555> cli | WARN|Waiting until the size of mount cache will be less than threshold
[02.04.2025 16:04:16.777] <39977555> cli | WARN|Waiting until the size of mount cache will be less than threshold

Here is a guide on Veeam Agent Vulnerability: Fix Veeam Agent vulnerability for Microsoft Windows. Also, see how to fix “The push installation of the agent failed for the computer – Error message (67) The network cannot be found“.

Steps to resolve AIX Veeam agent job startup delay

I have found where if AIX agent is running 4.5 or 4.6 on AIX 7.2 and later the performance issue can be encountered.  These agent versions will use ipV6 sockets.

Currently the agent does not have a work around to only use ipV4 sockets, but it can be addressed at the AIX OS layer by disabling mtu_bypass/largesend.

First you can see at aix if the mtu_bypass are “on”, using:

root@sappiqas (/)# lsattr -El en0 -a mtu_bypass
mtu_bypass on Enable/Disable largesend for virtual Ethernet True

Then, disable it using the following command:

root@sappiqas (/)# chdev -l en0 -a mtu_bypass=off
en0 changed

Note: Before you turn it off, ensure that no service is using mtu_bypass. After that, the agent job runs just fine. ​

I hope you found this article very useful on how to Fixing AIX Veeam agent job startup delay issue. Please feel free to leave a comment below.