12-16-2008
SAP swap recommendations
Hello all.
My company is installing an SAP ERP financials. The consultants are asking me to allocate 30Gbytes of swap. This is on a dedicated Linux box running Redhat 5 64Bit OS. It has 16GB of RAM.I have asked for an explanation but all I'm getting is that this is what SAP recommends. It seems really strange. Redhat recommends 1/3 times RAM for swap on RHEL5. I am seeing virtually no swapping going on. It seems to me if they need this much swap I should be adding RAM. My experience from way back it that too much swap on a linux box can cause problems. This was back in 2002 or so but I'm sure we were seeing really bad performance with too much swap that went away once we reduced it to 2GB of swap only.
My question is simple. Anyone out there running SAP with less swap than RAM? If so, are you experiencing and real problems?
Thanks.
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LEARN ABOUT CENTOS
xdbeswapbuffers
XdbeSwapBuffers(3) X FUNCTIONS XdbeSwapBuffers(3)
NAME
XdbeSwapBuffers - swaps front and back DBE buffers.
SYNOPSIS
#include <X11/extensions/Xdbe.h>
Status XdbeSwapBuffers(
Display *dpy,
XdbeSwapInfo *swap_info,
int num_windows)
DESCRIPTION
This function swaps the front and back buffers for a list of windows. The argument num_windows specifies how many windows are to have
their buffers swapped; it is the number of elements in the swap_info array. The argument swap_info specifies the information needed per
window to do the swap.
The XdbeSwapInfo structure has the following fields:
Window swap_window
XdbeSwapAction swap_action
swap_window specifies the window for which to swap buffers. swap_action specifies the swap action to use for this swap_window.
swap_action determines what will happen to the new back buffer of the swap_window it is paired with in the list in addition to making the
old back buffer become visible. The defined actions are as follows:
XdbeUndefined
The contents of the new back buffer become undefined. This may be the most efficient action since it allows the implementation to
discard the contents of the buffer if it needs to.
XdbeBackground
The unobscured region of the new back buffer will be tiled with the window background. The background action allows devices to use
a fast clear capability during a swap.
XdbeUntouched
The unobscured region of the new back buffer will be unmodified by the swap.
XdbeCopied
The unobscured region of the new back buffer will be the contents of the old back buffer
ERRORS
BadMatch
A non-double-buffered window was specified or a window was specified twice.
BadWindow
An invalid window was specified.
BadValue
An invalid swap action was specified.
SEE ALSO
DBE, XdbeAllocateBackBufferName(), XdbeBeginIdiom(), XdbeDeallocateBackBufferName(), XdbeEndIdiom(), XdbeFreeVisualInfo(), XdbeGetBack-
BufferAttributes(), XdbeGetVisualInfo(), XdbeQueryExtension().
X Version 11 libXext 1.3.2 XdbeSwapBuffers(3)