How to find out memory swapping to disk

[Gulam Mohiuddin_1]

I am not too sure whether any swapping is taking place or not at present. I am
a Oracle DBA and don't have much knowledge on HP-UX.

We have lots of Oracle database running on the server and I think that the
Oracle's Shared memory (SGA) is being swapped out to disk degrading the
performance of the dataabses on that server.

Server details: HP 9000 V-2500 HP-UX VER 11.00 64 Bits

Following is the output of vmstat and swapinfo command on our HP-UX 11.00
Server:

$swapinfo -ta
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE
dev 2043904 149816 1894088 7% /dev/vg00/lvol2
reserve - 778756 -778756
memory 636484 259456 377028 41%
total 2680388 1188028 1492360 44% - -

=======================================================

$vamstat -S 1 1
process memory
r b w avm free si so pi
0 1 0 37846 14669 505599 505599 0

If anybody can help me to find out how to confirm that the server is currently
swapping out to disk.

Thanks,

[Frank Broeer]

You can use HP Glance to see the swapping activity of you machine. You can find
glance on the Application CD?s
Have a look at DART47 Dec 99 CD 2

[Chris Anoruo_1]

check you kenel configuration parameters
allocate_fs_swapmap=1
swapmem_on=0 . If the parameters are not as stated, retune your kernel with the
values.
From you swapinfo -ta output, your system is swapping into memory instead of
the swap space of 2gb on lvol2

[Fernando Santana]

Hi, yes your system is swapping out to disk. A lot
of swapping out would cause memory faults and therefore
system performance degradation. If this is the
normal operation of your system, and you're already
being affected performancewise, you should add more
phisical memory to your HP. If the percentage used
gets too high adding an extra swap area can get you
out of trouble. I preffer to do this in vg00 if
there's space left, but it can be another VG.

#lvcreate -L SizeMB -C y -r n /dev/vg00

Add a line to your /etc/fstab file that looks like
this:

#/dev/vg00/lvol? .... swap pri=1 0 0

where /dev/vg00/lvol? is the resulting just created
LV from the previous step.

#swapon -a

Activate your swap area.

[Deivan Fusuy]

Gulam Mohiuddin - Asalaam-Ale-Kum,

It looks like you are having performance problems! There are several area that
need looking into.
Not knowing the size of the system memory on your V-class server and swapinfo
-ta is showing only 620MB approx. is used as a pseudo swap. Obviously you want
minimal paging to take place and SGA should not be paged out. With this limited
information I would recommend following initially.

1. HP's kernel parameter tuning document recommends swapmem_on to be disabled
on V class server if device swap is not large enough (2GB in your case). This
will put to use device swap. However, adding secondary device swaps would be a
good idea too.

2. If you have sufficient memory then you may want to lock the SGAs / shared
memory segment in memory. Check your init.ora file and look for
lock_shared_memory parameter setting. If it is set to false then your SGAs are
swapping out.
Send me an email if you have questions regarding this.
deivan_fusuy@hotmail.com
Regards,
DF