I worked at a company that thought they had bought their way to reliability with Sun, Oracle, and NetApp but we had a three-day-long outage when some internal NetApp kernel thing overflowed on filers with more than 2^31 inodes. Later the same company had a giant dataloss outage when the hot spare Veritas head, an expensive Sun machine, decided it was the master while the old master also thought so, and together they trashed the entire Oracle database.
Both hardware and software in those days were, largely, steaming piles of shit. I have a feeling that many people who express nostalgia for those old Unix systems were probably 4 years old at the relevant time. Actually living through it wasn't any fun. Linux saved us from all that.
My fingers still habitually run `sync` when they're idling because of my innumerable experiences with filesystem corruption and data loss on Linux during the 1990s. There were just too many bugs that caused corruption (memory or disk) or crashes under heavy load or niche cases, and your best bet at preserving your data was to minimize the window when the disk could be in a stale or, especially, inconsistent state. ext3, which implemented a journal and (modulo bugs) guaranteed constant consistent disk state, didn't come until 2001. XFS was ported to Linux also in 2001, though it was extremely unreliable (on Linux, at least) for several more years.
Of course, if you were mostly only serving read-only data via HTTP or FTP, or otherwise running typical 90s websites (Perl CGI, PHP, etc, with intrinsically resilient write patterns[1]), then Linux rocked. Mostly because of ergonomics and accessibility (cost, complexity); and the toolchain and development environment (GNU userland, distribution binary packages, etc) were the bigger reasons for that. Travails with commercial corporate software weren't very common because it was uncommon for vendors to port products to Linux and uncommon for people to bother running them, especially in scenarios where traditional Unix systems were used.
[1] Using something like GDBM was begging for unrecoverable corruption. Ironically, MySQL was fairly stable given the nature of usage patterns back then and their interaction with Linux' weak spots.
Both hardware and software in those days were, largely, steaming piles of shit. I have a feeling that many people who express nostalgia for those old Unix systems were probably 4 years old at the relevant time. Actually living through it wasn't any fun. Linux saved us from all that.