hedrick@topaz.rutgers.edu (Charles Hedrick) (08/21/87)
In article <2161@xanth.UUCP>, john@xanth.UUCP (John Owens) writes: > ... People have even made filesystems on > magtapes and mounted them read-only, but I doubt if they ever did it > for anything besides seeing that it could be done. Actually, Pyramid distribution tapes include a bootable read-only filesystem on tape. It is a smallish root system, with the utilities that you need for setting up disks and fixing badly crashed systems. It's a good last-ditch refuge for when all your disks are trashed and you don't want to just clear them and try again. Sun's equivalent is a file system image that you copy on top of your swap space, using the standalone copy program. Once you get it in, this gives you better performance than a filesystem on tape. And of course Sun is concerned about machines that don't have tape drives. But the tape file system is easier to bring up, and its performance is surprisingly good.
guy%gorodish@Sun.COM (Guy Harris) (08/21/87)
> Sun's equivalent is a file system image that you copy on top of your swap > space, using the standalone copy program. This wasn't Sun's idea; it dates back at least to 4.2BSD, and possibly earlier. If it wasn't present in 4.1BSD, it was probably done to avoid the need to make stand-alone versions of "mkfs" and "restore" for the 4.2BSD file system; V7 (and possibly 4.1BSD) were installed by running a stand-alone "mkfs" and "restore" to bring in a "dump" of the root file system, and proceeding from there. Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy guy@sun.com