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UDMG allows to define a complex folder structure for the storage of the local files. The final and temporary location of a file for a given transfer scenario can be set by means of the global configuration, or at the Server level, or by the transfer rule which itself depends on the combination of partner/server, account and the requested target path. This allows to split into different folder and/or filesystems according to the business cases, for security requirements, or access speed, or space management. For more details please refer to the UDMG Server configuration file, the creation and update of Server entities, and the creation and update of Transfer Rules.
The Temp Directory (also denoted as 'tmpReceiveDir') is only utilized for file transfer where UDMG is on the receiving end (either by actively downloading a file as a client, or by being pushed a file as a server). This is were where the partial content is stored until the completion of the file data exchange between server an and client. At the end of the transfer, the temporary file is moved to its target location that was defined by the transfer rule Local Directory (or the default value from the Server entity Receive Directory, or in turn by the default from UDMG Server global configuration).
All the final and temporary folder locations must be large enough to accommodate the expected volume of files and their retention period (to be handled outside of UDMG). For example, let's assume a transfer scenario with a daily download of a 1.5 Tb 5Tb file, a weekly retention is setup with the removal of file files older that 7 days, a setup where the temporary and final storage are on different filesystems. Considering solely this scenario, the temp storage must be greater than 1.5Tb and the final storage greater than 11 Tb11Tb. Ideally, both would require to be at least the double in size, to allow for transfer failures and retries.
Note that having the temp and final on the same filesystem would avoid the need for additional space and usually speed up the moving (intra-filesystem move operation versus inter-filesystem copy and delete).
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