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Silvan Michael Gebhardt

Unternehmer, Informatiker, Network Operator

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How to firmware upgrade the APC PDU 7921

I have one of these: APC PDU in my office.

Which works fine. Except if you want to fully manage it with observium and see the actual used wattage you should upgrade the firmware to the newest revision.

It’s a networked device, after all. So I did upgrade the firmware. Which works by going to their website and download the firmware upgrade package. Unzip it, and run the go.bat - yeah it’s windows. Their script asks for the IP; username, Password. No issue here. Except…. after upgrading, it told me it cannot reach the PDU anymore - neither could I, but it just took very long to reboot.

So I was not scared yet, but after upgrading them no webinterface worked. I was curious, and googled a bit around.

There are two files here: (I ignored apc_hw02_aos_202.bin since it’s an old version)


the installed firmware version is 3.7.4 so this is apparently a two part firmware image. both are a bit less than 2 Mbytes.

The PDU let me access it via FTP and behold, I can only see the AOS (which must stand for APC OS) on the flash. Drag-Drop the rpdu_374.bin file to the PDU, and suddenly the webinterface works instantly. Not even a reboot was needed.

So the firmware upgrade looses half the files, but FTPing it back works.

Don’t rename it though!