Is that swap utilization correct ?

[Rajesh SB]

Hi,

One of Compaq True64 UNIX V5.1A showing the swap info as below.

Swap partition /dev/disk/dsk0h (default swap):
Allocated space: 264420 pages (2.02GB)
In-use space: 58915 pages ( 22%)
Free space: 205505 pages ( 77%)


Total swap allocation:
Allocated space: 264420 pages (2.02GB)
Reserved space: 236187 pages ( 89%)
In-use space: 58915 pages ( 22%)
Available space: 28233 pages ( 10%)


In above swap info what is this
"Reserved space: 236187 pages ( 89%)".
Where it will be utilized.

How can I utilize reserved space?

FYI:
The following entry I found in the file /etc/sysconfigtab

vm:
vm_swap_eager = 0
swapdevice=/dev/disk/dsk0h
vm-swap-eager=1

Is it necessary to change any of above parameters.

You are valuable info is highy appreciated.

Thanks & Regds,
Rajesh

[Ralf Puchner · Accepted solution]

There are two different swapping modes: eager and lazy mode.

if you see the "reserved space" information then the system always swap out memory if it is used or not. e.g. an application allocates 100MB and doesn't use it, the system reserves 100MB on swap. In this mode, the memorylimit is the swapspacesize.

In the other mode the memorylimit is physical memory + swapspace. This mode works faster because the swapspace is only used if the physical memory is filled up or the application explicit allocates swapspace.

Have a look into the administration guide section swapspace for further explanations and samples.