swap space below 10% error message in tru64 unix

[berenger aguissi]

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.

[Venkatesh BL]

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]

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]

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]

try using 'diskconfig' to visually check the unused partitions in a disk.

[Ivan Ferreira]

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.

[berenger aguissi]

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]

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]

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.