Yes, having 4 is a little odd. We are struggling with this server. It sits 
almost idle most of the month then for 1 or 2 days it gets 60 to 80 thousand 
hits/hour. 
Not sure what to make of this current display of the swap space.

Bobby Bauer
Center for Information Technology
National Institutes of Health
Bethesda, MD 20892-5628
301-594-7474



-----Original Message-----
From: RPN01 [mailto:[email protected]] 
Sent: Wednesday, November 02, 2011 10:14 AM
To: [email protected]
Subject: Re: Odd swap space behavior

That's what you want when you're using "spindles", but on z, you're usually
talking about v-disks, which are really virtual disks in memory. When
they're not in use, they take up no space at all, but when you start using
them, they start to occupy real memory and become a burden. So you set
priorities on the swap spaces so that they each get used one at a time in
turn.

Ideally, you don't want to use them at all; they're a safeguard to keep the
image from coming down. When they are used, they're an indication that you
need more memory allocated to the image, and they give you a buffer to get
to the moment when you can safely cycle the image to add that memory. Having
four swap spaces allocated seems like a bit of overkill to me. It should be
sufficient to have one to be the buffer, and a second larger one to be the
trigger to increase the size of the image.

--
Robert P. Nix          Mayo Foundation        .~.
RO-OC-1-18             200 First Street SW    /V\
507-284-0844           Rochester, MN 55905   /( )\
-----                                        ^^-^^
"In theory, theory and practice are the same, but
 in practice, theory and practice are different."



On 11/2/11 8:25 AM, "Richard Higson" <[email protected]> wrote:

> On Wed, Nov 02, 2011 at 07:37:17AM -0400, Bauer, Bobby (NIH/CIT) [E] wrote:

> haven't done Linux on Z for a while, but I have always used the same
> "Priority" for the swapdisks
> so that linux could spread out the IO to several disks (preferably on separate
> spindles).
> This works well on x86 (real & VMware) and P-Series
>

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