Weird things happening when trying to add secondary swap and dump!

[Nick Zraika]

Hi,

I am in the process of setting up a secondary swap and dump device on HP-UX 10.20. I have increased maxswapchunks to its max value of 16384 to cater for future swap space which may be assigned.

For some reason, after issuing the swapon command i keep getting the message -

swapon: The kernel tunable parameter "maxswapchunks" needs to be increased to add paging on device /dev/vg05/lvol1.

Below is the output of sysdef showing that after the kernel was rebuilt the new parameter was taken into effect:
#sysdef
maxswapchunks 16384 - 1-16384 -

/stand/system also reflects the above.

Given maxswapchunks is set to 16384 and swchunk is set to 2048 i believe the system should be able to cater for "approx" 33gigs of swap. So why does it keep saying maxswapchunks needs to be increased, when its already at its max?

Please help!

[Dietmar Konermann]

Looks like a bogus message to me. See:
http://www.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062903050

Best regards...
Dietmar.

[Nick Zraika]

Things don't look promising i ran the following:

dd if=/stand/vmunix of=/dev/vg05/lvol1 bs=128k

got the following output:

#dd if=/stand/vmunix of=/dev/vg05/lvol1 bs=128k
61+1 records in
61+1 records out

re-created the volume

#lvcreate -C y -n lvol1 -r n vg05
Logical volume "/dev/vg05/lvol1" has been successfully created with
character device "/dev/vg05/rlvol1".
Volume Group configuration for /dev/vg05 has been saved in /etc/lvmconf/vg05.conf

#lvextend -L 1048 /dev/vg05/lvol1
/dev/dsk/c0t9d0
Logical volume "/dev/vg05/lvol1" has been successfully extended.
Volume Group configuration for /dev/vg05 has been saved in /etc/lvmconf/vg05.conf

I created the volume as strict/contiguous and with bad block allocation off as i want use this volume also as dump.

when i try to put swap on this volume:

#swapon /dev/vg05/lvol1
swapon: The kernel tunable parameter "maxswapchunks" needs to be increased to add
paging on device /dev/vg05/lvol1.

tried with -f also to no avail

#swapon -f /dev/vg05/lvol1
swapon: The kernel tunable parameter "maxswapchunks" needs to be increased to add
paging on device /dev/vg05/lvol1.


Really scratching my head here!

[SS_6]

Try to add swap through SAM just to eliminate any manual error possibility.

[Nick Zraika]

Tried that :(

SAM gave the same error...

i ran the following command to see what the kernel thought maxswapchunks was set too.

#echo maxswapchunks/D | adb /stand/vmunix /dev/kmem

and it returned 16384 which is correct..

Very very interesting..... i believe its a bogus error message!

[Steven E. Protter]

Hi,

1) Nick, 10.20 is out of support. If you must use it, i suggest you have the latest patch set installed.

2) Check the docs and see if you are exceeding some hard limit in the kernel which I would not know about since i have little 10.20 experience.

3) If any of our posts have been useful, please consider asisgning my colleages points. I have enough thanks.

SEP

[Sanjiv Sharma_1]

Hi Nick,

As HP-UX 10.20 is out of support by HP.

It is recommended to have the latest patch bundle installed.

[Dietmar Konermann]

I agree with the others... 10.20 systems should be patched to the latest level. Interesting here is PHKL_26064/PHKL_26063.

However, please post the result of this adb command:

# echo 'maxswapchunks/D\nswchunk/D\nnswapdev/D\nswdevt/10X\n\n\n\n\n\n\n\n\n' | adb /stand/vmunix /dev/kmem

Best regards...
Dietmar.

[Nick Zraika]

I appreciate everyone's persistance on this.. i agree 100% re the patching.. the problem i have is the customer has limited disk space and doesn't want to spend any more $$$. As for upgrading the OS, the application which is running on the server has been coded specifically for 10.20 (doddgy i know!) so i have been left to do with what i have :(

Below is the output of the command requested:
echo 'maxswapchunks/D\nswchunk/D\nnswapdev/D\nswdevt/10X\n\n\n\n\n\n' |adb /stand/vmunix /dev/kmem
maxswapchunks:
maxswapchunks: 16384
swchunk:
swchunk: 2048
nswapdev:
nswapdev: 10
swdevt:
swdevt: 40000002 1 0 0xFA000
0xFA000 2C9BC 1 0
1F3 3F2280
swdevt+28: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+50: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+78: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+0xA0: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+0xC8: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+0xF0: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+118: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+140: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0
swdevt+168: 0xFFFFFFFF 0 0 0
0 0 0 0
0 0


I have found something interesting though.... the system allows me to place 500mb of swap on another lvol i created in /dev/vg05!!! but it doesn't let me use it on /dev/vg05/lvol1 ?????????
getting more and more interesting..

[Nick Zraika]

Checked patches and did find either of the following patches installed:
#swlist -l product |grep PHKL_26064
#swlist -l product |grep PHKL_26063

Have these patches been know to fix this issue?

[Nick Zraika]

Checked patches and did "NOT" find either of the following patches installed:
#swlist -l product |grep PHKL_26064
#swlist -l product |grep PHKL_26063

Have these patches been know to fix this issue?

[Nick Zraika]

There's definately a bug..
I removed that 500m volume i created for swap /dev/vg05/lswap2 restarted server to disable the swap, and then tried creating it again and it didn't let me do it anymore??? hmmmmmmmm

error:
#swapon -p 2 /dev/vg05/lswap2
swapon: The kernel tunable parameter "maxswapchunks" needs to be increased to add
paging on device /dev/vg05/lswap2.

[Dietmar Konermann]

Sorry, I cannot confirm that the patch fixes this really weird problem. The swdevt looks fine also. Maybe we hit some 2GB barrier?

Anyway, it would be bad to waste more time for trouble-shooting and later on find out that it's an already fixed problem. So I urge you to patch this system first... if the customer needs to stay with 10.20 then patching is a must anyway. 'No disk space' is no argument against that.

Best regards...
Dietmar.

[Nick Zraika]

Thanx to all who posted their idea's.
I will put a business case forward to purchase new disk and bring the server to the latest patch level for HP-UX 10.20.

Will see how it goes after that!

thanx again.
Nick

[Jakes Louw]

This is a stupid question, but have you tried increasing SWCHUNK?

I see you are running the default of 2048 blocks. Increase yours to 4096 as a start (the limit is 65536 blocks).

[SS_6]

Jakes, Your question is very logical and I would suggest to increase kernel parameter through SAM because it will also tell if any other dependable parameter needs to be adjusted.

[Nick Zraika]

Thanks guys will try increasing the SWCHUNK parameter, i am very much against using SAM to recompile the kernel as it adds un-neccessary drivers which increases its size.I know what your saying however in the sense it may have a formula which depends on other parameters. I will look that up.
Will let you guys know how it goes...

thanks again.