Question about parallel and/or multithreaded 7-zip decompression

[rcxb]

@alpha754293

[…] mounting the formatted tape to that mount point, and then using rsync to send the data to tape.

So…I’m not sure how I would integrate mbuffer with rsync for that purpose.

You can use mbuffer just like “cp” to copy from the disk to the tape mount, and back:
mbuffer -m 1.9G -i /disk/path/filename.tar.gz -o /tmp/lto8/filename.tar.gz

In my experience, rsync gives about HALF the I/O performance of other file copying tools, even non-buffering ones, so I would avoid it anywhere performance matters..

(One of the files from the CAE/HPC application itself, when compressed into its own archive format, is currently about 5.5 TB itself.)

In that case, not a good fit for you. Of course you could split the file into parts, but that’s troublesome.

I would be interested to see:
a) what kind of compression ratios that it’s able to get?
b) and whether or not it can do parallel decompression?

There are several different compression options, so there’s no simple answer.

And then, it also states that it needs other tools like mksquashfs to create a populated filesystem, so I’m not sure how that works and how that would interact with the LTO-8 tape.

mksquashfs is used just like “tar” to create the file system with the files you want on it. The squashfs volume is just a single file, you can copy to any media.