Subject: Re: Suggestion: NetBSD source official ISO image
To: Carl Mascott <>
From: Todd Vierling <>
List: tech-install
Date: 12/11/2001 23:07:05
On Tue, 11 Dec 2001, Carl Mascott wrote:

: The subject is official NetBSD ISO images.
: There is exactly one non-package i386 official NetBSD ISO image
: (the install CD) and at < 97 MB it doesn't include source.
: Please refer to
: before responding.

Since I built the OS images on, I'd be happy to explain why doesn't currently ship multiplatform or source-code-laden ISOs at
this time; "bandwidth".  There's two issues at work here:

* Network bandwidth increases quite a bit at release time -- particularly
  for mirror sites pulling down fresh data via a ftp-crawl or rsync.  We
  chose single-platform ISO images to partition the data so it will be more
  likely to be relevant to the downloader.  (With this scheme, a separate
  ISO image with only source code is rather pointless, since the source is
  just 5 gzipped tarballs.)

  However, network bandwidth isn't the real killer; it is....

* Disk/memory bandwidth.  Were we to offer several different kinds of ISOs
  as has been requested, given the various FTP mirrors' known load, we'd
  basically be ordering a bunch of NetBSD FTP sites to hand over their core
  RAM and page themselves to death.

  The problem lies in the fact that there is redundant data -- both in the
  ISOs and in the standard release directories.  As a straw example, if one
  person is downloading the sparc64 ISO, one is downloading "Multiplatform
  1", and one is downloading sparc64 tarballs, all three of these users are
  accessing different parts of disk and buffer/page cache, even if the data
  is identical.  Add that up with the typical number of downloaders we have
  seen at a release, and even striped disksets have a very hard time keeping
  up with the load.

The NetBSD Foundation, and all of the educational institutions and private
organizations that host NetBSD mirrors, don't have unlimited hardware or
unlimited bandwidth as with some more market-popular ("penguin") OS's--even
though we have seen numbers of downloaders shockingly comparable at NetBSD
release time.  As a noncommercial entity, can't chug out huge
wads of data without hitting some practical limits.

To provide the most useful set of ISO images in the available resources, we
decided to create per-platform ISOs without source.  You can still download
the source code, of course, since it's just a handful of files.  But we
don't want to stuff source code into every one of those ISOs, leaving us
with a few dozen extra copies of the same data.  (Remember, NetBSD has a
*lot* of platforms.)

Now, this doesn't mean we won't ship a better variety of ISO images in the
future.  We have been beefing up available resources where possible, and
have been exploring other possible methodologies for reducing the
memory/disk bandwidth issues.  I'm hoping that can ship
multiplatform and other varieties of ISO images in the near future -- maybe
with 1.6, but I can't guarantee that.


(Since this post will now be in, others are free to
refer to it to explain this position.  8-)

-- Todd Vierling <>  *  Wasabi & NetBSD:  Run with it.
-- CDs, Integration, Embedding, Support --