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From: lara@sgi.com (Lara J Allen)
Newsgroups: comp.sys.sgi
Subject: Re: swap space
Message-ID: <1991Apr17.210257.15521@odin.corp.sgi.com>
Date: 17 Apr 91 21:02:57 GMT
References: <9104161701.AA06206@ccfiris.aedc> <1991Apr17.031917.15633@odin.corp.sgi.com>
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Organization: Silicon Graphics, Inc., Mountain View, CA
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In article <1991Apr17.031917.15633@odin.corp.sgi.com> olson@anchor.esd.sgi.com (Dave Olson) writes:
>In <9104161701.AA06206@ccfiris.aedc> mcdonald@AEDC-VAX.AF.MIL writes:
>
>| I am posting this for an associate:

might want to see if your company gets _Pipeline_  
  This is CSD's 'newsletter' to the world.  people
  under support should get it.  there was a fantastic
  article on how to redo swap space.
if not, email pipeline@sgi.com

>Completely back up the system (you could get buy with just /usr, but that
>is risky).  VERIFY that your backups are valid!
i too, cannot stress this enough.
please make certain you backed up what you thought you did.

i usually tell people to make two sets of backups.  one complete
  and one specific (/usr/people/$USER and /etc)

>Press return for the first 3 prompts, then type "label/set/part".
>Change the size of the swap partition (partition 1), and then change
>partition 6 to match (i.e., increase the start of partition 6 and decrease
>the size).  Then type "../sho/part" to make sure it is correct.  If so, type
>"../sync", then "/exit".  You are now back at the PROM monitor.

to determine how to change the size, you're going to need
  to look at the label and find out how many sectors/trac and
  how many tracks/cylinder.
The best way is: before bringing down the system, do a
  prtvtoc and print it out.  keep it next to you at all
  times.    

then, the magic equation is:

Total # of Cylinders = (Desired Size of Swap in Mbytes)/{(# bytes/sector)x
				 (# sectors/track)x(#tracks/cylinder)}

so, if a machine had 512 bytes/sector, 45 sectors/track and
  9 tracks/cylinder, and in this case, wanted 150M of swap,
Total # of Cylinders = 150000000/(512x45x9)
	   	     = 723.38
   		     = 724 cylinders

thus, the root would probably be 3 + 82
then the swap would be 85 + 725
then user would be 810 + whatever

you get the picture.

and like dave said, don't forget to rerun mkfs on the new user
  partition.  (i've seen a lot of problems where this was
  the cause)

lastly, please...once you've repartitioned...please don't
  reformat.


good luck!
if something i said doesn't make sense, let me know and i'll
  either put my foot in my mouth or clear up the mud

thanks!
lara

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