Date: Tue, 11 Mar 1997 16:46:06 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: jgreco@solaria.sol.net (Joe Greco) Cc: terry@lambert.org, scrappy@hub.org, marc@bowtie.nl, neal@pernet.net, hackers@freebsd.org Subject: Re: freebsd as a news server? Message-ID: <199703112346.QAA26363@phaeton.artisoft.com> In-Reply-To: <199703112227.QAA01054@solaria.sol.net> from "Joe Greco" at Mar 11, 97 04:27:23 pm
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> > Unless the information was locally generated, in which case it is not > > possible to recover it. If I post to a host running mounted -async, > > and that host does not guaranteed to put the article on disk before > > it responds to me, and crashes after the response before the article > > has been committed to stable storage, then my article is lost. > > Wrong, Terry, it doesn't have to be that way, just because it works > that way for some folks. You're building a case based on assumptions > that do not necessarily _have_ to be valid. > > In my case, when offered an article, it's offered to thirty peers > instantly, and sent to twenty eight of them long before the disk > head gets to where it will write it to disk. > > That's a pretty small margin for error. Of course, what you're > missing is that the post gets spooled to an area of the disk that > is NOT mounted -o async, first, and gets offered to multiple servers > before getting wiped, so if it doesn't make it out, something really > strange must have happened. If the article is not written to an -async mounted disk, then your site does not have the potential problem. > Welcome to '90's news server technology. I don't care what was true > five years ago. I don't care what the clueless newbie newsadmin is > doing, either. I think this goes beyond the scope of even the average clued newsadmin, actually. The failure modes for -async mounts are probablistic and non-zero was my major point, and you must take that into consideration. The orginal recommendation for -async mounts did not include the posting area being mounted non -async. If you'll reread my original article, you'll see I noted that as a workaround fo reliability problems in just this case. > > This is different thatn if it is just a read/mirroring server, since > > all articales which did not locally originate are recoverable, per > > your example above. The special case of locally generated articles > > is not. > > The unspecial case of locally generated articles is boring because we're > both smart enough to engineer a way around it. > > (I think.) Yes. But the average clued news admin is not aware of the issue without a discussion such as this one, IMO. If someone says "mount -async" without qualification, where is the clue supposed to come from? It would also be a bad idea for someone to say that, by extension, if mounting -async sped up news and that's a good thing, mounting -async to speed up other operations is also a good thing. > > Because the data is recoverable from other sources, and because your > > service availability requirements are scoped that downtime following > > a crash permits recovery to occur. Yes. > > What ARE you babbling about? I have no downtime after a crash. The statement is still valid in that context. The data is recoverable from oter sources and the scope is zero. It was not a dependent statement, so the first part still applies. Regards, Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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