In order for the -ZU switch to work, the database property, "Use LZ1 compression for attachments", must be enabled. If the property is not enabled, then the -ZU switch has no effect. The -ZD switch converts to Huffman regardless of the property setting.
For Domino 6.5.6 only, the following notes.ini parameter must be set in order for either switch to operate:
DEBUG_ENABLE_LZ1_REPAIR=1
The parameter can be set for the current Domino session by issuing the following command at the server console:
Set Config DEBUG_ENABLE_LZ1_REPAIR=1
To convert existing attachments from Huffman to LZ1 compression, perform the following steps:
1. Enable the database property, "Use LZ1 compression for attachments", found in Database Properties --> Advanced (beanie) panel.
2. From the server console, run the following command (without quotes):
"load compact -ZU"
To convert existing attachments from LZ1 to Huffman compression, from the server console, run the following command (without quotes): "load compact -ZD"
NOTE: The conversion to Huffman compression will take place regardless of whether the "Use LZ1 compression for attachments" property is enabled or disabled.