Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by Gopal » Fri, 03 Mar 2000 04:00:00



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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Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by Alan Stang » Wed, 08 Mar 2000 04:00:00



> 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 ?

Why don't you tell us what it should be doing.  Why do you think it should swap a process?  I'd suggest including some of the sar/vmstat numbers.

--


 
 
 

Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by fishi.. » Wed, 08 Mar 2000 04:00:00




Quote:> 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 ?

> * Sent from AltaVista http://www.altavista.com Where you can also

find related Web Pages, Images, Audios, Videos, News, and Shopping.
Smart is Beautiful

--
Solution to what?  Sounds quite normal to me.

John

Actual Sun Bug:
4110503 as_setprot heuristic gave my process a wedgie

Sent via Deja.com http://www.deja.com/
Before you buy.

 
 
 

Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by Gopal » Fri, 10 Mar 2000 04:00:00


I have missed including the side effects of this situation.

The Free memory sinks down to NIL and system locks out
inspite of 1GB of unused Virtual Memory. The only way to
regain normalcy is a Hard Power Recylce, coz, even console
stops responding. This has been seen on Sun Boxes
consistently. Is there any tool to find out the in-memory
Process statistics other than TOP ( which is less helping
in my situation ).

* Sent from AltaVista http://www.altavista.com Where you can also find related Web Pages, Images, Audios, Videos, News, and Shopping.  Smart is Beautiful

 
 
 

Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by Rich Siege » Sat, 11 Mar 2000 04:00:00


I've always been told that the free memory statistic in vmstat is mostly
useless since Solaris tends to grab most of the free memory for various file
and/or vnode caches and returns it to processes as memory demands increase.
As such, Free Memory is not a very good indicator of possible memory
contention.   I know most of our Solaris 2.6 systems show rather low free
memory and show no other signs of memory problems like high page and swap
rates.



>> 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 ?

>Why don't you tell us what it should be doing.  Why do you think it should

swap a process?  I'd suggest including some of the sar/vmstat numbers.

- Show quoted text -

>--


 
 
 

Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by Chris Thomps » Sun, 12 Mar 2000 04:00:00




>I have missed including the side effects of this situation.

>The Free memory sinks down to NIL and system locks out
>inspite of 1GB of unused Virtual Memory. The only way to
>regain normalcy is a Hard Power Recylce, coz, even console
>stops responding. This has been seen on Sun Boxes
>consistently. Is there any tool to find out the in-memory
>Process statistics other than TOP ( which is less helping
>in my situation ).

As the other replies have indicated, "free memory" isn't a good
indicator of anything much, but you obviously have a real problem.
It sounds like a kernel memory leak or a memory leak of locked
pages in a critical process. Get a crash dump: if you can't get
access to the prom prompt when it's totally seized up (is that
what you mean by "even [the] console stops responding"?) then
try doing it before the system gets to that stage. A bit of poking
around the crash dump should give some idea of where the memory
is going.

If the problem is a process rather than the kernel, then use of
"ps -eo pid,rss,vsz,comm | sort +1nr | head" (or use +2nr, but be
aware that large vsz doesn't necessarily indicate a problem) might
show you the offender.

Chris Thompson
Email: cet1 [at] cam.ac.uk

 
 
 

Free Virutal Memory is 1% even though Total Free Virtual Memory is above 1GB

Post by Jerry D. Harris Jr » Fri, 17 Mar 2000 04:00:00


Sounds pretty odd.  I am running something somewhat similiar without any problems....
Sounds like a memory leak.  Have you checked out the standard stuff???

1.  Solaris System patched to date?  Veritas patched to date?  Run patchdiag -l (lower case "L", to get all software(I think) to get a complete picture of
all patches.)  I typically install the recommended/security patch cluster and then run patchdiag and browse for any additional stuff I use.
2.  Since your on 2.6, are you running oracle?  Is that patched, there was a known memory leak, and certain features in 8.x  needed at least kernal patch
108151-16.  Also,  if you are, how big is your SGA?  For a 1 gig box I would keep the all SGA's summed up on that box down to 500M.  Also, how many users?
Dedicated connections?  If you have a high number of dedicated connections, that will reap any available memory you had, so consider using MTS.
3.  What other things are running on that box?  Are they up-to-date?  Are there any known issues?

One last thing, which probably won't help you situation by itself but SWAP should be at least 2x physical RAM.

-Jerry


> I have missed including the side effects of this situation.

> The Free memory sinks down to NIL and system locks out
> inspite of 1GB of unused Virtual Memory. The only way to
> regain normalcy is a Hard Power Recylce, coz, even console
> stops responding. This has been seen on Sun Boxes
> consistently. Is there any tool to find out the in-memory
> Process statistics other than TOP ( which is less helping
> in my situation ).

> * Sent from AltaVista http://www.altavista.com Where you can also find related Web Pages, Images, Audios, Videos, News, and Shopping.  Smart is Beautiful

 
 
 

1. free(8050000) above top of memory. Memory corrupt?

Hi,

I'm suddenly getting the following messages:

free(8050000) above top of memory. (memtop = 804f000 membot = 8049fb8)

I never got these messages before, and as far as I know I didn't change
anything on my system lately. I suspect faulty SIMMs. Is it possible
to get this message cause of that. Anyone got any ideas about this? My
setup is:

- Linux 1.3.59
- CPU: 486DX2-66
- 16 Mb RAM

Thanks for any pointers.

Ben.

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