Tunables

A few notes about AIX tunable parameters and device settings

To be continued...

The below mentioned 'Huncraft' is a friend of mine working for IBM. He works on performance problems every day.

Warning: These parameters are highly specific to the environment. Use them with care, and don't adjust more than one or two at once.

Virtual memory

> man vmo

> man svmon

> man vmstat

> man mkps, lsps...

vmo

Database standard based on Oracle and IBM recommendations

lgpg_regions= - depends on pagesize

lgpg_size=16777216 - almost always this number (4GB) - only when using lock_sga in Oracle

lru_file_repage=0 (see v_pinshm)

maxclient%=90

maxperm%=90

maxpin%=80

minperm%=3~10

maxfree=1088-20480

minfree=960-16384

page_steal_method=1 (in most cases)

strict_maxclient=1

srict_maxperm=0

v_pinshm=1

If lru_file_repage=0, then v_pinshm=1!

If minfree=16384, then maxfree=2048 and the ratio is always similar

---

From Huncraft:

vmo

lru_file_repage=0

maxperm%=90

maxclient%=90

minperm%=3

page_steal_method=1

Disk I/O, storage adapter, LVM and filesystem parameters

> man ioo

> man lvmo

> man mount (cio, dio, rbrw etc)

max_transfer

queue_depth

---

From Huncraft:

ioo

j2_nBufferPerPagerDevice=1536

j2_dynamicBufferPreallocation=256

numfsbufs=1024

pv_min_pbuf=1024

Network tunables

> man no

> man nfso

[1] Recommended value based on various sources, see references below.

[2] AIX 7.1 default values (most likely the same as in 6.1)

[3] ISNO values must be changed via chdev. They have different presets for each NIC type, for example, 131072/65536 for GbE cards.