Re: [TUHS] Zombified SCO comes back from the dead, brings trial back to life against IBM

[Tony Finch <dot@dotat.at>]

Dan Stromberg <drsalists@gmail.com> wrote:
>
> Please see https://stromberg.dnsalias.org/~strombrg/why-solaris.html for a
> list of benefits of 5.5 over 4.1.x.

A few of those are distinctly mixed blessings :-)

I learned about Solaris's in-kernel telnet the hard way, trying to debug a
system on which telnet would not work properly after rebooting. I think I
worked it out by trussing telnetd, which showed me that it was trying to
load a kernel module, and failing because we had chrooted it. A bit of
searching around told me what the module was for.

The Solaris automounter was neat - we did clever things with the userland
part, and it mostly performed well because the fast path was in the
kernel. Except that it didn't have a cache for ENOENT directory entries,
so requests for nonexistent paths always took a trip to userland, and (as
far as I could tell) these requests were serialized, and if you managed to
overload the automounter it would start returning bogus errors - I think
it was EPERM. Our Apache httpd started randomly returning 403 errors when
it tried to access a missing .htaccess (which it did on every request!)
and got EPERM instead.

The name service cache was also problematic. It was probably useful for
getpwnam() etc. on systems using NIS, but it behaved very badly on systems
that sent a lot of DNS queries through nscd. It worked much better for us
if we simply prevented it from running at all. And I'm not entirely sure
it was all that great for NIS: another problem I heard of second hand was
password files getting truncated when lots of users were trying to change
their passwords at the same time. My colleagues fixed that by ensuring all
password changes happened on the NIS master with suitable locking, and the
password files were periodically replicated with rdist instead of using
more normal NIS machinery.

Tony.
-- 
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