Did UNIX/Unix tapes have live file systems to dump in or tree of resources to pull from? Or something else!
@dexter Well, you couldn't use any Unix filesystem on a sequential medium like tape. But I do recall that (in the pre-disklabel days) it was common to use a low-level monitor routine to copy an installer filesystem (containing just a kernel and specialized init) from tape to the future swap partition of the boot disk, then manually boot from that to complete the install from the next "file" on the tape which was in tar/cpio format.

@wollman @dexter Lots of such tape images here: http://www.bitsavers.org/bits/Sun/

But, even older, the original DECtapes could be randomly read & written, so in hours (not moments) of desperation they could host filesystems.

Index of /bits/Sun

@aka_pugs @wollman @dexter

Pyramid did that with their install-tapes on 9-track...