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Operating System - Tru64 Unix
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how to free up memory resources in tru64

Danny Ramos_3
Occasional Contributor

how to free up memory resources in tru64

hi guys,

i've always been trying to figure out how to refresh my systems memory utilization. I am using an es40 tru64 version 4.0f and has been experiencing almost 100% memory utilization. I am expecting the application to release memory resources after each transaction, is this correct? or is it the responsibility of the OS as what the application developer claimed, to do the necessary housekeeping? If so, how do we refresh memory utilization in tru64 without doing reboot?

Michael Schulte zur Sur
Honored Contributor

Re: how to free up memory resources in tru64

Hi Danny,

100% memory utilization is not bad in itself. Are you experiencing any page out?
What kind of application are you using? Have you checked their requirements against the system configuration? Can you post
sysconfig -q vm?


Danny Ramos_3
Occasional Contributor

Re: how to free up memory resources in tru64

i haven't experienced page out yet, application being ran is developed using java, i am just wondering why my system can't reduce memory utilization even when all applications are being brought down. Is this a case of a memory leak?

below is the requested output:

# sysconfig -q vm
ubc-minpercent = 10
ubc-maxpercent = 100
ubc-borrowpercent = 20
ubc-maxdirtywrites = 5
vm-max-wrpgio-kluster = 32768
vm-max-rdpgio-kluster = 16384
vm-cowfaults = 4
vm-mapentries = 2386
vm-maxvas = 6979321856
vm-maxwire = 16777216
vm-heappercent = 7
vm-vpagemax = 65536
vm-segmentation = 1
vm-ubcpagesteal = 24
vm-ubcdirtypercent = 10
vm-ubcseqstartpercent = 50
vm-ubcseqpercent = 20
vm-csubmapsize = 1048576
vm-ubcbuffers = 256
vm-syncswapbuffers = 128
vm-asyncswapbuffers = 4
vm-clustermap = 1048576
vm-clustersize = 65536
vm-zone_size = 0
vm-kentry_zone_size = 16777216
vm-syswiredpercent = 80
vm-inswappedmin = 1
vm-page-free-target = 128
vm-page-free-swap = 74
vm-page-free-hardswap = 2048
vm-page-free-min = 20
vm-page-free-reserved = 10
vm-page-free-optimal = 74
vm-page-prewrite-target = 256
dump-user-pte-pages = 0
kernel-stack-guard-pages = 1
vm-min-kernel-address = 18446744065119617024
malloc-percpu-cache = 1
vm-aggressive-swap = 0
vm_page_color_private = 0
vm-map-index-count = 64
vm-map-index-rebalance = 128
vm-map-index-enabled = 1
vm-map-index-hiwat = 4
vm-map-index-lowat = 2
new-wire-method = 1
vm-segment-cache-max = 50
vm-page-lock-count = 64
gh-chunks = 0
gh-min-seg-size = 8388608
gh-fail-if-no-mem = 1
private-text = 0
private-cache-percent = 0
Venkatesh BL
Honored Contributor

Re: how to free up memory resources in tru64

If you have 'collect' datafiles, then you could scan thru it to see if any process is having a memory leak problem.
Michael Schulte zur Sur
Honored Contributor

Re: how to free up memory resources in tru64


ubc-maxpercent = 100
This is a reason, much memory is used. You advise the unified buffer cache to use up to 100% of the available memory.
If you are using oracle then this parameter should be set much lower to avoide having to buffer in the os and in oracle.
Try sysconfig -r vm ubc-maxpercent=70 and you should notice a reduced memory utilization.
Another command is ipcs -b to see if any application creates a shared memory segment and leaves it behind.


Re: how to free up memory resources in tru64

This is my way to calculate some critical values. When all services are up and running and used then you can count of all:

Minimum values are
ipcs -q|wc -l

ipcs -s|wc -l

ipcs -m|wc -l

2147475456 (=2G-8Kbit)

ps -ef|wc -l

All the running process ~ max_process_per_user

expr `ps -efm|wc -l` - `ps -ef|wc -l`

All the running threads ~ max_threads_per_user

ubc_maxpercent: You can count this also
vmstat -P
see the section "Managed Pages Break Down"

("free pages" + "inactive pages" + "ubc pages") * 100/"Total"

The root-user does'n have limit on the process and threads!

If you use very big values, start to thing that everything is in the big tables witch fragmented ie. too big values means overhead, less memory, users and so on.

ubc_minpercent = 3
ubc_borrowpercent = 3
ubc_maxpercent = 66

If you have a big big physical memory then calculate how much memory is a 3%, this gives to you image how muct data stays in the memory to waiting flush!

Victor Semaska_3
Esteemed Contributor

Re: how to free up memory resources in tru64


As mentioned by others 100% memory utilitzation isn't necessarily a bad thing. It depends on whether your system is paging out a lot.

Have you considered using sys_check to see what it recommends for system parameters? The command would be:
# /usr/sbin/sys_check -all > sys_check.htm
Look at the 'View Warnings' section.

To get the latest version of sys_check use this URL:


There are 10 kinds of people, one that understands binary and one that doesn't.