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swap space below 10% error message in tru64 unix

berenger aguissi
Frequent Advisor

swap space below 10% error message in tru64 unix

Hi,


The error message above keeps on coming for about one month now.
In /var/adm/messages system log the following is mentioned : "servername> vmunix: vm_swap_init: swap is set to eager allocation mode". I would like to know the implication of this message on the swap space, please.

Also when I was analysing the swap space bellow 10% problem, I realise with swapon -s command that the swap space is 2 GB. Swap space is located on partition disk0g. ADVFS is the default filesystem used for the entire system. The physical RAM memory is 4.5 GB.
Please tell me the procedure I have to follow to safely increase the swap space without causing harm to the productive environment.

Thanks for your contribution !


Regards.
Berenger.
8 REPLIES
Venkatesh BL
Honored Contributor

Re: swap space below 10% error message in tru64 unix

Identify a disk or disk paritition that is free to be used as additional swap and then use the command: "# swapon /dev/disk/" to increase the swap space. This doesn't require a reboot. To make it permanent (survive reboot), you need to update the /etc/sysconfigtab file. See manpage of 'swapon' for more info.

There were multiple discussions regarding the swap mode in this forum. Use the 'Search' tool to learn about them.
berenger aguissi
Frequent Advisor

Re: swap space below 10% error message in tru64 unix


Please tell me how I can easily identify a free disk partition ?
In another word how can I create one without adding a new physical disk ?

Thanks for your contribution !
Michael Schulte zur Sur
Honored Contributor

Re: swap space below 10% error message in tru64 unix

Hi,

I think your swap space is currently on dsk0b
what os version are you running?
In 5.x this allocation mode is set in /etc/sysconfigtab
I usually set it to zero because programs usually request virtual memory but never use it.
You can identify a free partition with
disklabel -r dskx
x beeing a number. Unused partitions usually have unused in fstype. A partition is characterized by an offset from disk start and a length. You can edit a partition with disklabel -e dskx

greetings,

Michael
Venkatesh BL
Honored Contributor

Re: swap space below 10% error message in tru64 unix

try using 'diskconfig' to visually check the unused partitions in a disk.
Ivan Ferreira
Honored Contributor

Re: swap space below 10% error message in tru64 unix

I think that your swap area is low in relation to physical memory. I always use swap space at least = RAM.

If you don't have free space on any disk, you will have to destroy a filesystem, repartition the disk and create a smaller filesystem an use the remaining disk space as swap. Swap partitions should be in low I/O disks.

You could buy another disk and configure it as swap partition.

You could also set the
vm:
vm_swap_eager = 0

In the sysconfigtab file, this will prevent the reservation of swap space that is not used. See the Syste configuration and tuning for a detailed explanation of this parameter. We have vm_swap_eager = 0 configured on our systems.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
berenger aguissi
Frequent Advisor

Re: swap space below 10% error message in tru64 unix

Hi,

There is something I don't understand :
When I used disklabel to display the partitions on the disk I found partitions d, e, f marked as unused. But when I try to use any of them as swap space with swapon command I get an overlapping error stating that the partition is already open.

Please help !

Regards.
Berenger.
Michael Schulte zur Sur
Honored Contributor

Re: swap space below 10% error message in tru64 unix

Hi,

as I wrote in my last post, a partition is characterized by its offset and length. Partitions can not overlap because they would destroy each other's data. Just because a partition is labelled unused does not mean its region is available.

Michael
Venkatesh BL
Honored Contributor

Re: swap space below 10% error message in tru64 unix

This is where 'diskconfig' will help. It will visually show you which partitions are used. When you select an unconfigured partition, it will either re-adjust the size of that partition or say that it cannot be used.