Signature disk Usage reached 91% exceeding the threshold of 90% (NOT REPORTS)

Sophos-tech solved this for me. Possible it helps another too.

1. My FW (an old virtual appliance) has not a lot of disk space.

2. There are old savi & avira files ... possible from previous upgrades. After removing them, i have 60% disk usage again:

at my device:

ls -hl $(find /content/savi_1.00/ -name "*.tar.gz")
-rw-r--r--    1 vpnporta heartbea  288.3M Aug 17 12:53 /content/savi_1.00/1.0.19828/savi_19828.tar.gz
ls -hl $(find /content/avira_4.00/ -name "*.tar.gz")
-rw-r--r--    1 vpnporta heartbea  245.9M Aug 17 16:52 /content/avira_4.00/1.0.424761/avira_424761.tar.gz

Sophos: "To fix the 90% usage issue for this box, these pattern file can be removed. So, it should minimize total content usage."

... and it works !!

thank you so much for this simple and direct answer. perfect.

better the support, i say

You know, that this statement above, from Dirk, was provided by the Sophos Support? 

It's all the worse that support isn't able to simply tell me this solution.
Oh yeah, I forgot that the error hasn't occurred in the last 9 years LOL

Toni, please stop replying to my threads here.

I need direct, neat solutions and not standard phrases.
The time I waste answering such standard sentences and wrong answers from Sophos is horrible.

How can you block someone in the community?

It's all the worse that support isn't able to simply tell me this solution.
Oh yeah, I forgot that the error hasn't occurred in the last 9 years LOL

Toni, please stop replying to my threads here.

I need direct, neat solutions and not standard phrases.
The time I waste answering such standard sentences and wrong answers from Sophos is horrible.

How can you block someone in the community?

The solution to your problem is quite easy: 
Sophos raised the needed space for the Disks of primary from 4 GB in 17.5 to minimum of 16 GB in V18.0. 

Customers with older Appliances do not have the needed space and could potentially run into space issues, because the appliance does not offer enough space. 

https://docs.sophos.com/nsg/sophos-firewall/19.5/Help/en-us/webhelp/onlinehelp/VirtualAndSoftwareAppliancesHelp/SoftwareAppliance/index.html 

New installation all utilize more space.

The outcome here is essentially: You can clean up the signature partition all the time or you could reimage the system with a bigger Disk and restore your backup. This will essentially resolve this problem.

Sophos cannot make IPS pattern and other pattern "smaller" and utilizing 4 GB over the long run is hard. 

You can take this answer or refuse to. But that are the hard facts based on your issue. 

Additionally we are internally following up on this topic and investigating based on the feedback by dirkkotte and this case here to identify a potential issue.