Checking Swap space from OS level in HPUX

[Former Member]

Hi All,

We have some issues with swap in our SAP production system when I checked the ST06 Tcode

Swap

Configured swap Kb 20,971,520 Maximum swap-space Kb 54,389,460

Free in swap-space Kb 8,945,160 Actual swap-space Kb 54,389,460

And when I checked from the OS level ,it gave me the following result

swapinfo

Kb Kb Kb PCT START/ Kb

TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME

dev 1048576 658208 390368 63% 0 - 1 /dev/vg00/lvol2

dev 19922944 889824 19033120 4% 0 - 1 /dev/vg00/lvol9

reserve - 19423488 -19423488

memory 33417940 24781076 8636864 74%

Does it mean that total swap space is (1048576 + 19922944)KB which is 20GB?

If yes ,then how to increase the swap space in UNIX based systems?

SWAP SPACE = 3*RAM? If yes ,do we need to put swap size =60 GB?

In ST06

what is the difference between CONFIGURED SWAP-SPACE and ACTUAL SWAP-SPACE?

Regards,

Prashant

Edited by: Prashant Shukla on Oct 13, 2008 4:21 AM

Edited by: Prashant Shukla on Oct 13, 2008 4:23 AM

[Former Member · Accepted solution]

hi prashant,

it seems that your system had been configured swap size about 54,389,460 Kb on OS level. From SAP Note (I forgott the number), swap size for 64 bit system are 3 x RAM with maximum size 20 GB.

So, you had configured too much swap on your system.

ardhian

http://sapbasis.wordpress.com

[Former Member · Accepted solution]

Hi,

Thanks for ur reply but when I checked it from OS level why it is showing only 20GB ?

What's the diff between configured and actual swap space ?

I checked SAP Notes :146289 and 153641

They clearly says that swap space should be atleast 20 GB plus 10 GB for additional Instance for the server.

In our landscape we have CI and 4 dialog instance connected to it

that means our swap space should be 20 + 10*4=60 GB

We are having HPUX server and ST06 Swap values are

Swap

Configured swap Kb 20,971,520 Maximum swap-space Kb 54,389,460

Free in swap-space Kb 8,697,960 Actual swap-space Kb 54,389,460

Do we need to increase the SWAP Space to increase the system performance?

What is difference between configured swap and actual swap space ?

SAP Note 1112627 clearly says that SWAP SPACE = 2* RAM for HPUX servers.

What do you guys say about this?

Regards,

Prashant

Edited by: Prashant Shukla on Oct 13, 2008 5:15 AM

Edited by: Prashant Shukla on Oct 13, 2008 5:53 AM

[Former Member · Accepted solution]

Hello Prashant Shukla , if you have problems for SWAP on HP-UX you correctly read 1112627 note.

Do not listen to advice rather 20 GB, it only MINIMUM. Read note In more detail for your situation.

Regards.

[Former Member · Accepted solution]

Hi Sergo,

Thanks for uy reply ,I have already gone through this note and it says SWAP should be 2 times the RAM in ST06 there are 4 values for swap coloumn could you pls tell me the diff between configured swap and actual swap?

Regards,

Prashant

[Former Member · Accepted solution]

Configured SWAP are the sum of you "real" SWAP == 19922944 +1048576 = 20971460

actual looks like sum of your real memory and SWAP 20971460 + 33417940 = 54389400

Regards.

[Former Member · Accepted solution]

Hi Sergo,

Thanks a lot for ur help.Now things are getting clear.

Now we have 54 GB of SWAP SPACE and RAM is 33 GB ,there are lot of swaps happening in ST02.So do you think I should increase the swap space to 66 GB. At any point of time free swap space is normally around 8 GB.or I should increase the parameter values in ST02 which are showing in RED Mark?

Regards,

Prashant

[Former Member · Accepted solution]

First of all you need to analyse the "the parameter values in ST02 which are showing in RED Mark" and tune your system, it is necessary to read through closely notes before change of that or...

About SWAP .... All depends on congestion of a server and it is necessary to look in details each case, I saw a server with 64 Gb memory and only 24 GB SWAP as your situation ....

Regards.

[Former Member · Accepted solution]

Thanks Sergo, I will try to tune the parameters could you pls tell the procedure to increase the SWAP Space in HP UX system.

Regards,

Prashant

[Former Member · Accepted solution]

We use SAM for it, try to find on HP site more information like this http://docs.hp.com/en/B2355-90950/ch06s03.html

Regards.

[Former Member · Accepted solution]

Thanks