Re: install guide draft

[Christopher Curran <ccurran redhat com>]

Joshua Wulf wrote:
> Ruediger Landmann wrote:
> > Mani A wrote:
> > > I had a look at some parts of
> > >
> > > http://rlandmann.fedorapeople.org/Installation Guide/en-US/html
> > >   
> > Many thanks! We need eyes on this.
> > > "7.22.4. SMP Motherboards and GRUB
> > > In previous versions of Fedora there were two different kernel
> > > versions, a uniprocessor version and an SMP version. In Fedora 11 the
> > > kernel is SMP-enabled by default and will take advantage of multiple
> > > core, hyperthreading, and multiple CPU capabilities when they are
> > > present. This same kernel can run on single CPUs with a single core
> > > and no hyperthreading. "
> > >
> > >
> > > This is being repeated since FC-4-6?
> > >   
> > Did the native kernel have multiprocessor support before F9? 
> > http://docs.fedoraproject.org/release-notes/f9/en_US/sn-Kernel.html 
> > (whatever version it was, the text should be clarified to name it 
> > specifically)
> >
> > This note will become less and less relevant with each release – at 
> > what point should we drop it though?
> > > "Swap should equal 2x physical RAM for up to 2 GB of physical RAM, and
> > > then an additional 1x physical RAM for any amount above 2 GB, but
> > > never less than 32 MB.
> > > So, if:
> > > M = Amount of RAM in GB, and S = Amount of swap in GB, then
> > >
> > > If M < 2
> > >     S = M *2
> > > Else
> > >     S = M + 2"
> > >
> > > Using this formula, a system with 2 GB of physical RAM would have 4 GB
> > > of swap, while one with 3 GB of physical RAM would have 5 GB of swap.
> > > Creating a large swap space partition can be especially helpful if you
> > > plan to upgrade your RAM at a later time.
> > > For systems with really large amounts of RAM (more than 32 GB) you can
> > > likely get away with a smaller swap partition (around 1x, or less, of
> > > physical RAM)."
> > >
> > >
> > > The formula is not correct. Or is this the result of some special 
> > > study?
> > >   
> > The formula is the current recommendation in Red Hat Enterprise Linux 
> > (see http://kbase.redhat.com/faq/docs/DOC-15252 ) and is what 
> > anaconda will create by default when installing Red Hat Enterprise 
> > Linux or Fedora. I don't think we should change this recommendation 
> > unless anaconda's behaviour changes as well.
> >
> > I think the text makes it pretty clear that this recommendation is 
> > only indicative; it's prefaced "If you are unsure about what size 
> > swap partition to create..."
> >
> > Do you think we need to draw more attention to this being a "rule of 
> > thumb"?
> >
> > Cheers
> > Rudi
> What idiot wrote that formula? (it was me ;-) )
>
> Reading its preceding text and looking at the formula, I think it 
> should have been:
>
> If M < 2
>     S = M *2
> Else
>     S = (M - 2) + 4
>
> if there are less than 2GB in the machine then you should double it = 
> M * 2
> if there are more than two gigs then you need the 4GB for the first 
> two gigs, then 1GB for each 1GB above 2GB
>
> Which part are you calling out as wrong? The formula as regards its 
> preceding text, or the whole thing?
This could be used. You have approval to convert it :)
http://kbase.redhat.com/faq/docs/DOC-15252

FYI, we should also mention machine's with over 8GB probably don't need 
more than 1GB of swap. If the machine starts swapping people should 
change their swappiness parameter or kill the memory hogs.

--
Chris Curran 
Technical Writer for Virtualization and Emerging Technologies
Phone: +61735148302 (UTC+10)
Brisbane, Australia. Red Hat, Inc.