Summary: RE: How to disable round robin paging

	I've got a lot of interesting messages to the question below. The
most important ones were that:
	1. There is a solution to this as suggested by Lieven Marchand and
this was to change the value of swap_maxcontig from the default 1 Mb to =
2GB
and=20
	have as a secondary effect round robin paging disabled. However, he
also pointed out that this is highly experimental and the ones willing =
to
try this on their production systems are on their own. I was not =
willing to
try hence I still have no feedback on this solution.
	2. The second (indirect) answer is that applications tend to reserve
upfront large quantities of memory upfront from which often a half or =
even
one third actually use. So, the fact that swap apear to be used means =
that
in fact that virtual memory was reserved, not necesarilly used. Of =
course,
because of the above, there will not actually be disk paging activity =
and
subsequently no performance problems. Adrian Cockroft personally =
pointed me
that a lot of memory shortage problems can be solved by just =
configuring
more swap (taking care if 32 bit kernel is used, that none of them is =
larger
than 2GB). In that way, applications which reserves virtual memory will
reserve not physical memory but disk swap space. This makes sense.
	Thanks everybody who bottered to respond !
	Best Regards,
	George DONE=20


> I ran in the following annoying "feature" of Solaris: Round Robin =
paging.
> This are the facts:
> 1) the space over 2 GB in a swap device is ignored
> 2) if you have more than one swap device, Solaris use them all in a =
round
> robin fashion, several pages on each swap device.
> Now this is good if you put each swap device on a separate
> volume/metadevice, because spreads the disk load. But if you need =
12GB of
> swap, that means you should use 12 separate disks to create 6 =
mirrored
> chunks of 2GB. This is way too many disks used for that.
> Alternativelly, you could place more than one swap metadevice/volume =
on
> the
> same pair of mirrored disks but you will soon notice bad performance
> because
> of long disk seeks.
> Now the question is:
> How can I disable this round robin and force Solaris to do paging on =
only
> one volume/metadevice and only when the first one is all used to turn =
to
> the
> second one ? The gotcha here is that most of the time I use only 1 GB =
or
> so
> of swap for paging and I need to configure 12 GB only to insure I =
will not
> run out of virtual memory in worst case batch run-scenario. The =
machine is
> already filled up with physical memory at full capacity.
>=20
> Regards,
> George DONE
> http://www.sunmanagers.org/mailman/listinfo/sunmanagers
>=20
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