## Calculating total virtual memory on Solaris 8

### Calculating total virtual memory on Solaris 8

Hi,

I am having some trouble calculating total virtual memory on our Solaris 8
servers.  The box has 2048MB of RAM and a 2048MB swap partition.  So, the
total virtual memory should be 4096MB (4GB).  Running the "swap  -s"
produces the following output:

# swap -s
total: 1109000k bytes allocated + 7968k reserved = 1116968k used, 2671016k
available

I expected to find the total amount of VM by simply adding the amount used
with the total available (in k-bytes).  Using the values above, this
calculation is 3787984K (leaving about 308MB short of 4GB).

What am I missing here?  Does Solaris 8 have some sort of "minfree" space
for VM that is not shown?  What is the absolute best way to determine how
much memory is being used (and/or available)?

Thanks,

-Ron

### Calculating total virtual memory on Solaris 8

> Hi,
> I am having some trouble calculating total virtual memory on our Solaris 8
> servers.  The box has 2048MB of RAM and a 2048MB swap partition.  So, the
> total virtual memory should be 4096MB (4GB).  Running the "swap  -s"
> produces the following output:
> # swap -s
> total: 1109000k bytes allocated + 7968k reserved = 1116968k used, 2671016k
> available
> I expected to find the total amount of VM by simply adding the amount used
> with the total available (in k-bytes).  Using the values above, this
> calculation is 3787984K (leaving about 308MB short of 4GB).
> What am I missing here?  Does Solaris 8 have some sort of "minfree" space
> for VM that is not shown?  What is the absolute best way to determine how
> much memory is being used (and/or available)?

I don't know that it explains all of it, but the kernel will reserve RAM
at boot time before the VM kicks in.  Those kernel pages are not part of
VM and are unswappable.  I would have expected it to be less than 300M,
but I can't think of other places for it to go...

I don't know the best way to find the amount of used kernel pages.

You are seeing the best way to determine how much memory is available to
normal, VM using processes.

--

Got some Dr Pepper?                           San Francisco, CA bay area
< This line left intentionally blank to confuse you. >

Configuration: Sun Ultra 450
Software
O/S: Solaris 2.6 sparc
Volmgt: Veritas Volume Mgmt
root disk is encapsulated ( including rootvol,
swapvol )

I have been observing this in about 25 Unix servers here.
Each of the servers has 1GB of MainMemory and have 1GB of
Swap Space defined. When Swap statistics are taken ( either
with Sar or vmstat ) system shows Free Memory <= 1% under
full load conditions. But system does not seem to use the
Virtual Memory nor try to swap out processes and make room
for the new processes.

Can anybody suggest a solution ?? Did anyone come across
any such situation ?

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