Databases
cancel
Showing results for 
Search instead for 
Did you mean: 

prngd[2272]: Could not fork: Not enough space in hp-ux

SOLVED
Go to solution
Shehan
Super Advisor

prngd[2272]: Could not fork: Not enough space in hp-ux

Hi all

I have rp4440 server running hp-ux 11 v1 and also running Oracle 10g. Problem is this data base does not respond sometime when there is a quite high load. Server is having 32GB memory and I saw always memory utilizing 80-90% when there is load. Also I saw below message in the syslog and GPM show some CPU bottleneck,disk bottleneck as well as swap is not enough warning occasionally.

Feb 25 16:25:17 DataWH prngd[2272]: Could not fork: Not enough space

Please advice me if you have prior experience on this issue.

Regards
Nirukshitha
25 REPLIES
Duncan Edmonstone
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Do you have sufficient swap? What's the output of "swapinfo -tam"

HTH

Duncan

HTH

Duncan
Jeeshan
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

what is the output of this commands

#sar -b 5 5

#sar -v 5 5
a warrior never quits
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Duncan

Please see the attached commands outputs.Also I monitored system is always utilizing swap almost 100%. Please check this and let me know the status.

Regards
Nirukshitha


Duncan Edmonstone
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

You have a 32GB system with only 4GB of swap.

As an absolute minimum you should have at least 25% (8GB in your case) of memory size available as swap. In your case I'd look at going right up to 50%/16GB of swap.

See the following docs for more guidelines:

http://docs.hp.com/en/B2355-90950/ch06s03.html

HTH

Duncan

HTH

Duncan
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Duncan

As per your suggestion, for the my system you have recommended me to increase up to 16GB. Is that correct?

If it is correct, can I increase existing 4GB swap space up to 16 GB or Do I need to create another logical volumes for 12GB? Please advice...

Regards
Nirukshitha
Duncan Edmonstone
Honored Contributor
Solution

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Well swap has to be contiguous, so I doubt you'll be able to extend that existing swap partition. I'd just create another lvol of 12GB in size and use that - remember these swap areas likely won't ever get *used*, the space just gets *reserved* in case it needs to be used.

HTH

Duncan

HTH

Duncan
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Duncan

As you propose, it seems to be better if we can create another lvol with 12GB for swap space. My worry is it seems there is no 12GB free space in the local disk. So, can I create this lvol in another VG at external storage?

Regards
Nirukshitha
Steven E. Protter
Exalted Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Shalom,

As you propose, it seems to be better if we can create another lvol with 12GB for swap space. My worry is it seems there is no 12GB free space in the local disk. So, can I create this lvol in another VG at external storage?

Putting swap in local storage is a bad idea.

If this system is new, you might want to reinstall the OS properly and avoid these issues.

Normally HP-UX requires swap to be a minimum of 50% physical RAM.

Yes, you can probably put the additional 12 GB of space on external storage, however vg00 might not have enough PE's left to allocate space on an external disk.

It would be much better to reduce a file system on the local disk and keep swap there.

The problem with putting swap on external storage is that if there is an unplug of the fiber network your system halts due to loss of access to swap space.

Not a good situation at all.

This system has been a bit abused and for long term stability, you probably want swap on some local disk.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Duncan Edmonstone
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

SEP,

>> Putting swap in local storage is a bad
>> idea.

Is that waht you meant to say, as the rest of your post seems to indicate otherwise?

>> If this system is new, you might want to
>> reinstall the OS properly and avoid these
>> issues.

Agreed - that would be the best policy, but this looks like a prod system - presumably if it is, that sort of outage will have to be planned. Adding a seperate swap volume in the short term will resolve that.

>> Yes, you can probably put the additional
>> 12 GB of space on external storage,
>> however vg00 might not have enough PE's
>> left to allocate space on an external
>> disk.

Well it doesn't all have to go in vg00 - you can have swap in seperate VGs, just so long as you have *some* in vg00 so you can get into single user/LVM maintenance mode.

>> The problem with putting swap on external
>> storage is that if there is an unplug of
>> the fiber network your system halts due
>> to loss of access to swap space.

>> Not a good situation at all.

Unplug a fiber cable on a system with only data on the SAN, and to all intents and purposes the system is hung anyway - after all we don't run systems just for the OS, we run them for the apps! Anyway, this just leads us back in to the old "boot from SAN" argument again, and I know we'll just have to agree to disagree on that one.

Besides, presumably Nirukshitha has at least 2 connections to his SAN?

Nirukshitha, to summarise:

i) In the long run SEP is correct - get all your swap on local disks if you're booting off local disks, at least if you lose the SAN, you can still get to an OS prompt. The simplest way to do this (assuming the disks in vg00 are big enough) is using an ignite backup/interactive recovery where you'll get the chance to change the size of swap.

ii) In the short term to prevent the erors you're seeing add some external swap - it can go in a seperate VG, just make sure you assign it a lower priority than your primary swap volume on vg00. That way it won't be used until primary swap is full.

HTH

Duncan

HTH

Duncan
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Stevan

Understand the situation about the keeping the swap in external storage. If external storage is down, system may be stuck due to low swap space.

Anyway I will try to get rid of the utilized space from the local disk and try to keep the 12GB swap space in the local disk.BTW, we are unable to reinstall the system as the systems is being used since 2004.

Also, I would like to know the steps in order to create 12GB swap space in the VG00.Please assist me on that.

Regards
Nirukshitha
Steven E. Protter
Exalted Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Yes, I meant to say NON-local.

Thanks. No points for this.
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Dear friend

Glad to say that there is a high possibility of getting additional space from the local disk(VG00) by deleting unwanted space.So please let me know most suitable method for increasing swap?Either external storage or internal . Also, as Duncan said this systems is having two redundancy paths and mutipath is being configured with XP24000 external storage. Please assist me.

Regards
Nirukshitha

James R. Ferguson
Acclaimed Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi:

I'm not going to comment on the local vs. SAN discussion. Duncan has already made the points I would.

You don't need to add your secondary swap device on vg00 if you don't have room there; put it anywhere you can.

To add a 12GB secondary swap, do:

# lvcreate -C y -r n -L 12000 -n lvolN /dev/vgXX

# swapon -p 0 /dev/vgXX/lvolN

# echo "/dev/vgXX/lvolN ... swap pri=0 0 0" >> /etc/fstab

...obviously, change the 'XX' and 'N' to meet your specific volume group and logical volume values.

Regards!

...JRF...
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Jeames

If we create the swap in the same VG00, can we use same steps in order to create secondary swap?

Also , as I know " swapon -p 0 /dev/vgXX/lvolN" setting the priority of the swap. If we use "0", will this be a secondary swap? or first piority?


Regards
Nirukshitha
James R. Ferguson
Acclaimed Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi (again):

By definition, primary swap is the device file swap in 'lvol2' of vg00. The swap priority has nothing to do with primary versus secondary as the definitions are used. You can have _multipe_ "secondary" swap devices but only one "primary".

The priority of primary swap is one (1). You can set secondary swap priorities to the same or a different value. Using the same would mean any swap activity is interleaved between the devices of equal priority. This is potentially benefical but potentially detrimental both in terms of disk head movement.

In the end analysis, you do NOT want to actually swap. You need the space for reservation. That is, whenever a process is created (unless there is a deferred swap reservation for the process), swap space is accounted for by the kernel. This is called a reservation. That is, the actual space is *available* or reserved should the process actually need to be paged.

Remember too that you must activate any secondary swap during startup. This is the reason for including entries for secondary swap devices in '/etc/fstab'. See the 'swapon(1M)' manpages for more information.

Regards!

...JRF...

Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi

What's the reason for utilizing swap space ?


Regards

Nirukshitha
Duncan Edmonstone
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Nirukshitha,

You need to know the difference between *using* swap space and just *reserving* swap space.

I'm sure you know that HP-UX, like most modern OSs is a "Virtual Memory" system - that is the processes in it can map to more memory than you have physically installed in the system.

Swap space is there for when the system comes under real memory pressure. In this situation rarely accessed pages of real memory are "paged out" onto the swap partition to free up memory for pages that are more regulalry accessed. In more severe situations, the memory of an entire process that hasn't been on the run queue in a while will be swapped out to the swap partition.

Read more here:

http://docs.hp.com/en/B2355-90672/ch06s02.html

To be sure that it is always in a position to do this "paging out" or "swapping out", HP-UX reserves swap space when a process allocates memory. This swap space won't actually get used (written to), unless paging/swapping actually occurs.

I think in your case you were simply reserving swap rather than using it. You can check whether you have started paging out, by running:

vmstat 2 10

and looking at the po column. SIgnificant numbers here means you are paging out, and should either reconfigure Oracle to use less memory, or install more memory in your system (and of course increase swap space when you do).

HTH

Duncan

HTH

Duncan
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi

My local disks are mirrored.So , Do I need to mirror newly created secondary swap's ?

If so , let me know the command in order to mirror this swap logical volume.anyway I am going to follow below steps to create secondary swap.


# lvcreate -C y -r n -L 12000 -n lvol11 /dev/vg00

# swapon -p 2 /dev/vg00/lvol11

# echo "/dev/vg00/lvol11 ... swap pri=2 0 0" >> /etc/fstab

Please correct if I am wrong.

Regards
Nirkshitha

Avinash20
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Yes, this is correct..
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Avinash20
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Since you are creating an LV you need to create mirror

lvextend -m 1
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Avinash

Can we use below command to mirror when creating lvol?

# lvcreate -m 1 -C y -r n -L 12000 -n lvol11 /dev/vg00

If so, I think we don't want to use lvextend command.
Please advice...

Regards
Nirukshitha
Avinash20
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Yes, the command is correct

But could I have the vgdisplay output.
How did you find our that you are having 12GB of free space.

If there is mirror you need to calculate the space, since the FRee PE's are distributed across the disk

Hope you have calculated it correctly
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Shehan
Super Advisor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

Hi Avinash

You mean if we need to create 12GB swap space , we need to create 24GB lvol with the "-m 1 " in order to get 12GB swap space.Am I correct ?

Regards
Nirukshitha
Avinash20
Honored Contributor

Re: prngd[2272]: Could not fork: Not enough space in hp-ux

No,

To have swap LV with mirroring, yo need 12GB of primary disk and 12 GB on mirror disk. Hence total 24 GB.

Could you post the output of vgdisplay -v
We can let you know the max free space available to create a lvol and make mirror of it.
"Light travels faster than sound. That's why some people appear bright until you hear them speak."