OK, that means you are not forced to go with Zip-wrangling (temp file creation/usage) being performed on the local (PC) side by virtue of the FTP protocol itself (
Zips cannot be opened/manipulated across FTP connections) but the 'wrangling' still has to be done somewhere (7-Zip, for example, has several settings you can tweak in this respect on Tools menu > Options > Folders in its File Manager, but there is no setting to 'use temp files or not' - the program decides this for itself).
As I understand it, the usage (or not) of one or more temp files in SB is similarly governed (decided) by the 3rd-party compression engine (DLL), and you cannot specify whether or not this happens - the compression engine decides this for itself (presumably 'intelligently', on the basis of number of files and/or total size of archive), and normally uses - if anything - the user's TEMP location for this purpose. All you can do is specify an alternative location using the profile setting
Compression > Advanced > Temporary directory.
for it to use if it decides to. As specifying anywhere else on your PC would still mean the contents need to be transferred 'back and forth', and presumably the option (as alluded to in the contextual Help) of using a RAM-disk on the PC for added speed is out of the question because of the 'gross' size of the archive, the only option you could try is setting Temporary Directory to a location on the NAS 'adjacent to' (
but not 'inside' *) the scope of the profile - something like
\\NAS\SHARENAME\BACKUP\ <<< where this represents your Destination path, and
\\NAS\SHARENAME\BUFFER\ <<< this is used as the Temp Directory setting (path) - note the effective segregation
You might thus avoid transferring the contents of the archive 'wholesale' across the LAN connection, but this means the actual 'wrangling' (manipulation of the old archive to produce a new archive) would be done over the LAN connection instead of just over an internal SATA bus, etc. My guess is that it will make little difference (or possibly be worse, especially if your NAS has sluggish firmware), but you can always try it and see.
As for whether to use individual Zips or a single-Zip (one-Zip-for-all). I tend to err on the side of individual Zips, on the basis that it may only take one byte of corruption to render an archive file useless, and I'd prefer that to be an archive representing one file, and not to be one Zip with
all my data in it. I'm therefore prepared to put up with the probably less efficient storage (total space used for individual Zips exceeding size of a single-Zip containing same data). But I'm sure other people think differently, possibly on the grounds of 'portability'.
* unless you want it to 'tie itself in knots' / set up a positive-feedback situation...using a \BACKUP\ subfolder (or equivalent) for the Destination is vital, otherwise (whether you use \BUFFER\ or not) your temp area will be inside the scope of \SHARENAME\ anyway (and not segregated like it needs to be)
