From: jeh@cmkrnl.com
Newsgroups: vmsnet.uucp
Subject: Re: NEWS / DECUS UUCP Integration
Date: 28 Jul 92 03:57:42 GMT
Organization: Kernel Mode Consulting, San Diego, CA

In article <1992Jul25.215126.4562@ecl.psu.edu>, fenner@jazz.psu.edu 
(Bill Fenner) writes:
> I have been tuning our NEWS setup for the past year.  We do NEWS adds
> distributed over several nodes.  We have a BITNET feed as well as a couple
> of NNTP feeds.  Moving news_manager to the news [item] disk would basically
> only mean that we'd have less space for articles [...]

not really.  You are missing another point of the news 2.0 code, which is that
the newsskim is run once per hour.  This is true even if you have more than an
hours' worth of rnews batch jobs queued up, because rnews always invokes
newsskim.com (which checks to see if it's been run within the hour, and if it
has, it just exits). 

The result is that the forwarding files in the news_manager subdirectories
don't stay there very long. 

Given, for example, a feed of 20 MB (uncompressed) per day, forwarded to three
sites:  You need an average of 20 MB of "dynamic" space on the .ITM disk for
the item files... plus a bit more to allow for cross-posted files. However,
that 20 MB is less than 1 MB per hour, average.  So your forwarding files will
only take up a peak of about 3 MB (1MB per neighbor), because after they've
been there an hour they'll be picked up, compressed into files in the
uucp_spool dir, and deleted from news_manager. 

There is also the odd day when your feed has been down all weekend and you
get THREE days' worth of news all in one burst.  So any prudent news manager
keeps free space equal to several days' worth of item files on the news_device
disk.  But news_manager will *still* only hold an hour's worth of feed at a
time.  

to put it another way:  news item file retention periods are measured in days,
sometimes weeks, while  the retention period of the files in the news_manager
forwarding subdirectories averages just half an hour.  Hence the amount of
dynamic space required for forwarding files is tiny compared to that required
for item files.  Hence, putting the forwarding files on the news item files
disk should not be a problem:  If you have enough room for the day's worth
(and, occasionally, several days' worth) of item files, you surely will have
enough room for an hour's worth of forwarding files as well. 

(What if the uucp_spool disk is full and can't take any more outbound stuff?  In
that case, three things happen:  (a) If there isn't enough room for an incoming
batch, rnews won't allow more news item file adds until free space on the news
item disk clears up.  (b) uucp refuses to accept incoming files, but will allow
outbound files to be transferred, so that if the cause of low disk space on the
uucp disk is lots of outbound files, they can be drained off to their
destination nodes.  (c) the uucp postmaster gets notified by mail of low free
space on the uucp disk, so that if the cause is something OTHER than crud in
the spool directory, she or he can go clean it up.  After which everything
unwedges itself (save that in extreme cases, RNEWS batch jobs resubmit
themselves as held jobs, and must be restarted manually).)

In short, please check out the extensive disk space checking procedures that
Mark has put into NEWSSKIM.COM and NEWS_RNEWS.COM... before you decide that
you really MUST put NEWS_MANAGER other than on the news items disk due to 
"dynamic free space" considerations.  

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
uucp 'g' protocol guru and release coordinator, VMSnet (DECUS uucp) W.G., and 
Chair, VMS Programming and Internals Working Group, U.S. DECUS VAX Systems SIG 
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh