SUMMARY: SunBlade1000 Recommended Swap File Size(s) - Solaris 8

From: Dave Warchol <>
Date: Fri Oct 18 2002 - 14:32:12 EDT
The summary is a little late, I apologize.

Thanks to:  Mike Salehi
                   Darren Dunham
                   Kevin Buterbaugh
                   David Foster
                   Tim Chipman
                   Jim Vandevegt, and,
                   Hichael Morton

What I found is that there is no definitive answer, part of it is based
on what you need to run, 
I've included the responses below:

You do not need to do it, but if you want to save dumps the swap has to
= 2G memory then  add the apps/oracle/CAD requirements if it's more

What do you need the swap for?
Configuring more than you need is a waste of drive space.  Configuring
less than you need could cause you to run out of VM if an allocation

     This really depends on your application.  Sun boxes can run with
swap whatsoever as long as you're sure the box has enough RAM that
never need to page or swap.  However, even in that scenario most people

will still configure some swap just to be able to catch an OS dump if
box panics.  With 2 GB of RAM in your Sun Blades, unless the
vendor makes a different recommendation, I'd configure 2 GB swap. 
just my 2 cents worth, however...

I'd go with 2GB swap. The 2x "rule" gets a bit silly with
larger amounts of RAM. Just my .02

in most cases on new gear with lots of memory, the 2x rule isn't
hard-and-fast, but it really depends on how you are using the gear.
ie, SunRay servers are meant to need a LOT of swap for example
"typical workstations" (with 2 gigs ram?!) probably don't need 4 gigs
swap. If I'm expecting lots of users (especially dormant
then again, disk is cheap (more or less) so too much swap isn't a "bad
thing" other than wasting disk space

The size of your VM space depends on the memory requirements of what
you want to run. 
Figure out your requirements, multiply by 2, and set paging (swap)
space accordingly.

2 x memory is not a bad rule of thumb, but sometimes can be a waste. 
On the other hand disk space is cheap and it sounds like you have
If you're running the 64-bit kernel, you can't have too much. (I have
crashed a 
32-bit machine by making the VM space > 4GB.) It's also not too hard to
add paging space, 
even on the fly. A good administrator always tries to leave some disk
set aside for new
 file systems or additional paging when needed :-).

In the real old days, swap was 3 X actual memory and 3.5 X for
sun does not recommend this any longer (as 2001 classes).  
Personally, I would use 1024MB for swap.  Regardless, if the amount you
is not enough, you can create additional swap space to augment your
swap partition/slice.  
A created swap file would be "integrated" into the swap fs and should
not cause any 
service degradation. (man swap should show you how.)

Thanks again everyone,
Original Post:
Hello managers:
        I did some poking around without finding any definitive
  I need to build a couple of boxes, each box having 2GB memory and a
 single 17GB internal drive.  A large SCSI attached array will be
 to each box later.  Some of the filesystems (internal and external)
 be shared out.  The old rule of thumb used to be swapsize = 2 x
 but I am not sure this still applies.  I will summarize.
sunmanagers mailing list
Received on Fri Oct 18 14:39:29 2002

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