How to increase swap space in aix

how to increase swap space in aix

Increase your available swap space with a swap file

Dec 12,  · How to increase AIX swap space. "lsps -a". This will display something like: Page Space Physical Volume Volume Group Size %Used Active Auto Type. hd6 hdisk0 rootvg MB 1 yes yes lv. This means that hd6 is the logical volume used for paging. To increase it, use the following command: "extendlv hd6 10G". This will add 10G of space to hd6, now reboot and then re-run "lsps -a" or you can simply use the "topas" command to check the paging space available. Dec 14,  · To increase it, use the following command: “extendlv hd6 10G” This will add 10G of space to hd6, now reboot and then re-run “lsps -a” or you can simply use the “topas” command to check the paging space available.

Today's Posts. Quick Links. Search Forums. Show Threads. Show Posts. Add additional swap place on AIX server. Registered User. Join Date: Mar Can anyone help me the detailed procedure and commands to follow to add additional swap on aix server. My system shows following as of nowCode :. Last edited by Don Cragun; at PM. Join Date: Feb The maximum theoretical size of one paging device is 64 GB.

You have paging device hd6 which is 6 GB. Theoretically you can expand it by 56 GB. Before expanding you have to answer the following questions: - how much memory does your application require? Which processes are now in the paging space and which of the running processes overuse the memory resources you have? After you answered the questions and if you still want to have more paging space, you can look in rootvg using lsvg rootvgif you have enough space in the volume group, and how to get past level 11 on use boxmen create additional paging space with mkps or expand the existing with chps.

This User Gave Thanks to agent. Join Date: May Your system shouldn't need to use it under normal circumstance and it should be there only for contingency. The size of paging space should be in some relation to the real memory, like the size of a jerry can should reflect the cars gas consumption. And like the jerry can it should be there but under normal circumstances never be used. I hope this helps. Join Date: Sep It would also be interessting when the paging to PS occurs.

Depending on the oslevel of your OS it could also maybe handled by adjusting some tuning parameters. If you want to investigate what is using the paging space at the moment you can issue: Code :. Last edited by zaxxon; at AM.

Reason: typo. Hello All, Thank you for your help. I checked the physical memory being only 13GB and left the idea of increasing swap size as of now. I will get back in case of any progress. Just an additional info - if you don't get all processes listed, try adding ALL to svmon like: Code :.

The real command to look, what lays in paging space is something like: Code :. Code :. Shell Programming and Scripting. In the attached file I am trying what does maize mean in english use awk to extract multiple values and create the tab-delimited desired output. I can extract from the values to the side of the keywords, but most are above and I can not Hello, How is it possible to free swap memory on AIX.

I dont wont to reboot the server. Add additional numbers to file. Hi, I am a newbie to AIX. We have 2 AIX5. Could you please help me as to how I need to do that? Thanks, Rakesh 4 Replies. I how far is pauls valley to oklahoma city an unsupported legacy server: uname -a AIX ibmms01 3 4 A4C00 Following a period of poor performance, it was investigated using vmstat There upto 10 blocked kernel threads reported, and free memory was down to Aix 5.

When i run the cfgmrg command and after de lspv command, i can see my disk but i think it's missing some drivers to get operational. Thank's for your help. For example, when you get a website from Lycos, you'll have an advertisement in the right corner. How to? As far as I can see, Lycos includes a javascript RedHat Commands.

OpenSolaris Commands. Linux Commands. SunOS Commands. FreeBSD Commands. Full Man Repository. Advanced Search. How to increase swap space in aix Us. Forum Rules. Mark Forums Read. Thread Tools. Moderator's Comments:. Please use CODE tags to display program input, program output, and code segments; not for your entire post. View Public Profile for gull Find all posts by gull View Public Profile for agent.

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About this series

Nov 16,  · You do this with the swap command (see Listing 6) in AIX 7 or by using the individual mkps and chps commands create paging space with logical partitions. Listing 6. Using the swap command #swap ?l device maj,min total free /dev/hd6 10, 2 MB MB. Depending on the oslevel of your OS it could also maybe handled by adjusting some tuning parameters. If you want to investigate what is using the paging space at the moment you can issue: Code: svmon -P | awk '/Pid/ {a=$0; getline; if ($5!= 0) {print a RS $0}}'. Column . Dec 03,  · Adding additional paging space: Use mkps command. bash# mkps -a -n -s 32 myvolvg paging00 bash#. Verify the newly added paging space: Once added, you can see the paging space in /etc/swapspaces.

It also drills down into the tuning parameters for the paging and organization of your virtual and physical memory within AIX Version 7. Part 2 focuses on the detail of actual memory subsystem monitoring and discusses how to analyze the results.

Part 3 focuses specifically on swap space and how best to tune your VMM settings to provide for optimum swap space configuration and performance. Just what is swap paging space? It all starts with the VMM. Because of its purpose, it is a critical component of overall system performance. As an administrator, you need to know how to monitor and tune your paging parameters.

The paging space itself is a special logical volume that stores the information that is currently not accessed. You must make sure that your system has adequate paging space.

If the paging space is too low, entire processes can be lost and the system can crash when your space fills up. Although it is important to reiterate that paging is a normal part of VMM, it is even more important you really understand how the kernel brings the process into RAM—too much paging definitely hinders performance.

AIX 7, through tight integration of the kernel and VMM, makes use of a methodology called demand paging. In fact, most of the kernel itself resides in virtual memory, which helps free up segments for other processes.

You will find that the tuning you do is based on what type of system you have. For example, systems that are using an Oracle Online Transaction Processing OLTP type of database usually have specific recommendations on how much swap space to configure and how to tune the paging parameters.

As discussed in previous installments of the series see resources on the right , you cannot really tune your paging settings unless you really know what is going on in the host system. You need to understand the tools to use, how best to analyze the data that you will be capturing, and familiarize yourself with best practices for implementing your paging space.

In our experience, the number one cause for a system crash is running out of paging space. If you read this article carefully and follow its recommendations, this should never happen to you.

In this section, we provide an overview of how AIX 7 handles paging, define swapping and paging, and drill down into the different modes of paging space allocation.

These concepts help you understand subsequent sections on monitoring, configuring, and tuning. Most administrators think of paging as something that is onerous. Paging is actually a very normal part of what AIX 7 does, due to the tight integration of its kernel with the VMM and its implementation of demand paging. The way demand paging works is that the kernel only loads a few pages at a time into real memory. If it cannot find it there, a page fault occurs, and this signals the kernel to bring more pages into RAM from disk.

One advantage of demand paging is that the paging space does not have to be particularly large, because data is constantly being shuffled between paging space and RAM.

This caused a condition where disk space would be allocated that was never used. Demand paging, in essence, avoids the condition where this disk space is allocated for no purpose. Swapping of processes is kept to a minimum, because many more jobs can be stored in RAM.

This is true because only parts of processes pages are stored in RAM. What about swapping? Though often used interchangeably, there is a subtle difference between paging and swapping. As discussed, only parts of the process are moved back and forth between disk and RAM with paging.

When swapping occurs, you are moving entire processes back and forth. For this to happen, AIX 7 suspends the entire process prior to moving it to paging space. It could then only continue to process when it is swapped back into RAM at a later event. As a UNIX administrator, you are probably already aware of some of the concepts of paging and swapping.

AIX 7 provides three different modes of paging space allocation: deferred page space allocation, late page space allocation, and early page space allocation. The default policy of AIX 7 is deferred page space allocation. This works by making sure that the allocation of paging space is delayed until the time that it is necessary to page out the page, which ensures that there is no wasted paging space.

In fact, when you have a large amount of RAM, you might actually never even use any of your paging space see Listing 1. Listing 1. Only three percent of paging space is used in Listing 1. Note as well that the checksum on the paging space is disabled, as shown by the 0 under Chksum. Checksums can help to improve the reliability of the paging space. You can change the checksum using the chps command, or when creating new paging spaces using the mkps command.

Listing 2. Listing 2 illustrates that the default method, deferred page space allocation, is being used. To disable this policy, you need to set the parameter to 0. This activates the system to use the late paging space allocation policy. Late paging space allocation causes paging disk blocks not to be allocated until its corresponding pages in RAM are touched.

This method is usually intended for environments where optimum performance is more important than reliability. In the scenario presented here, a program can fail due to the lack of memory. What about early page space allocation? This policy is usually used if you want to make certain that processes will not be killed because of low paging conditions. Early page space allocation pre-allocates paging space. This is the opposite end of the spectrum from late paging space allocation.

It is used in environments where reliability rules. AIX 7 also supports garbage collection of paging space, which means that disk space used as paging blocks can be forcibly recovered in the event of your machine running out of paging space for a particular workload and set of applications. Garbage collection can be used to help eke out even more memory from your system and help improve the performance in workloads with a range of applications being used concurrently.

This allows you to configure less paging space than you might necessarily need by allowing pages to be recovered. Garbage collection works in a number of configurable ways through the deferred page space allocation policy.

The default method is to perform the collection after the pages have been read back into memory. In this case, the pages are stored on disk, and also exist in memory, but are not deleted from the disk so that if the page has to be written out again but with no changes , there is no performance hit.

There are two key parameters, npsrpgmin and npsrpgmax , which set the number of blocks when re-pagein garbage collection starts and then it should stop. Two further parameters, rpgclean and rpgcontrol , specify how the garbage collection should operate. The rpgclean parameter defines whether the garbage collection is started on pages that are modified the default, 0 , or pages that are simply read from the paging space 1.

Setting to the latter may increase the incidences of garbage collection and make more pages available, but may impact performance. The rpgcontrol supports three options and controls when garbage collection is performed with reference to the npsrpgmin and npsrpgmax options. The default value of 2 specifies that garbage collection occurs irrespective of the limits. A value of 1 indicates that read accesses are processed. A value of 0 disable freeing of paging space disk blocks.

An alternative to the garbage collection when pages are read in and written out is for the kernel process pgsc to scrub memory, identifying the pages that have been written to disk, but which now appear in memory and that have not been written out to disk again. This frees the paged blocks on the paging device so that they can be used by other applications. Page scrubbing is a more intensive process than the pagein scrubbing, but has the benefit that it can free pages that have been created on disk but which are never actually written to the paging space.

Like pagein scrubbing, the operation is configured by vmo. The npscrubmin and npscrubmax parameters specify the number of free paging space blocks where scrubbing starts and when it stops. The scrub parameter enables or disables scrubbing default is disabled. The scrubclean parameter enables or disables the scrubbing of pages that are allocated but which have not been modified. For both types of page scrubbing, on systems where the paging space is regularly low, you may want to configure a more aggressive scrubbing schedule to make more pages available for all the applications and workload that you need to support.

The simplest way of determining the amount of paging space used on your system is by running the lsps command see Listing 3. Listing 3. You looked earlier at the -a flag. We prefer using the -s flag, because the -a flag shows only paging space that is being used while the -s command gives you a summary of all paging space allocated, including space allocated using early page space allocation. Of course, this only applies if the default method of paging allocation was turned off.

Next on the plate is vmstat. Part 2 of this series discussed vmstat in great detail, which is one of our favorite VMM monitoring tools. We find that it is the quickest way to determine what is going on in your system. If there is a lot of paging and thrashing going on, you will find it here. Listing 4. Listing 5. How can you tell this? First of all, look at the po column. This signifies that pages are consistently being moved back and forth between disk and RAM.

You should also see a bottleneck on your system, as the blocked processes and wait times are abnormally high. The freelist is also lower than it should be. In looking at the freelist with the vmo command, you determined that the number was This means that this number should not be falling below the mark. Ordinarily, we would say it is not a problem when your freelist is low but, in this case, it is below where it should be.

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