swap memory

[kacou]

How can i check and increase the swap of my system?
HP-UX
# uname -r
B.11.31
# model
ia64 hp server rx7640
#

[Torsten.]

"swapinfo -a" should list your swap devices.

[James R. Ferguson · Accepted solution]

Hi:

Use:

# swapinfo -tam

...to see your swap configuration.

Use 'vmstat' (or 'glance') to monitor swap activity. Look for page-outs ("po"). Single digit values are OK; double-digit values signify memory pressure.

To add additional swap space, choose a non-vg00 volume group. Make the swap priority different from that of your primary swap. I like secondary swap to be used preferentially to primary swap; i.e. with a lower number where the primary swap device priority=1. Do something like:

# lvcreate -C y -r n -L 4096 -n lvol1 /dev/vg01

# swapon -p 0 /dev/vg01/lvol1

# echo "/dev/vg01/lvol1 ... swap pri=0 0 0" >> /etc/fstab

Regards!

...JRF...

[kacou]

# /usr/contrib/bin/machinfo
CPU info:
4 Intel(R) Itanium 2 9000 series processors (1.6 GHz, 18 MB)
533 MT/s bus, CPU version C2
8 logical processors (2 per socket)

Memory: 65468 MB (63.93 GB)

Firmware info:
Firmware revision: 9.022
FP SWA driver revision: 1.18
IPMI is supported on this system.
BMC firmware revision: 3.01

Platform info:
Model: "ia64 hp server rx7640"
Machine ID number: eb87f752-e16b-11dc-8f9b-4f29fda6bf11
Machine serial number: DEH4803F2C

OS info:
Nodename: SVR-EDW
Release: HP-UX B.11.31
Version: U (unlimited-user license)
Machine: ia64
ID Number: 3951556434
vmunix _release_version:
@(#) $Revision: vmunix: B.11.31_LR FLAVOR=perf
# swapinfo -a
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 81920000 0 81920000 0% 0 - 1 /dev/vg00/lvol2
reserve - 425312 -425312
memory 63766620 9786196 53980424 15%
#

[Torsten.]

Why do you want to increase the swap?

Your current config is large and not used currently.

[Dennis Handly]

>Torsten: Your current config is large and not used currently.

How can you tell? Without the -t, there is no simple total line. Without the -m, there are too many digits to grok. ;-)
Yes, it seems that 80 Gb is way too much device swap.

[James R. Ferguson]

Hi (again):

I agree with Torsten. Why do you want to increase your swap space? You have the kernel 'pseudoswap' enabled as evidenced by the "memory" line in the 'swapinfo' output, so you can use ~75% of memory for swap reservation (a good thing).

Are you experiencing ENOMEM errors on fork() for instance? Have you monitored swap utilization?

If on the other hand someone (a vendor perhaps) gave you some "rule" that your swap space needed to be some factor of your memory, disregard the advice until you have emperical evidence that you really need more.

Regards!

...JRF...