Post upgrade Kernel modifications

[Andrew Moody_1]

Dear all

rp5470 was 3 x 875Mhz proc and 12Gb of RAM
now 4 x 857Mhz and 16Gb of RAM

rp7410 was 4 x 750Mhz proc and 8GB of RAM
now 8 x 750Mhz proc and 16Gb

Any suggestions for which Kernel parameters should be being tuned to make best use of this extra hardware

Thank you

[Jannik]

I just been something like this and I found this document very usefull:
http://docs.hp.com/en/TKP-90202/TKP-90202.pdf

This was recommended by HP:
kctune -B dbc_min_pct=1
kctune -B dbc_max_pct=1

but also have a look at the following:
vx_ninode, nproc, nkthread, nproc, maxuprc, maxssiz_64bit, maxssiz, maxuprc, msgtql, msgmap, msgseg, semmni, shmmni, vps_ceiling, ksi_alloc_max, msgmni, ncsize, semmns, semmnu.

At least you should max the shmmax to the memory 16*1024*1024*1024 - 20% = 13GB.

But all in all it depends on the application. and the after you take it live with the application monitor it with glance and tune it as you go.

[Sandman!]

Hi Andrew,

Look at increasing swap since you have doubled the memory on your rp7410. Only caveat is that swap needs to be contiguous. You'll have to take a look at your configuration to find out if this can be done with the exisitng disks or if you need to purchase disks bigger than the current.

~hope it helps

[Patrick Wallek]

Those dbc_min_pct and dbc_max_pct setting don't make much sense on a 16GB system.

A setting of 1 (meaning 1 percent of RAM) would set a static buffer cache of 163 MB on a system with 16GB of RAM. That is woefully low.

I would probably set dbc_min_pct to 5 and dbc_max_pct to 10. This would give a minimum buffer cache size of 800MB and a maximum size of 1600MB.

[Andrew Moody_1]

Maybe I'm being daft and revealing my inexperience but I've no idea why I'd need to increase swap on a machine that has doubled it's memory and that wasn't swapping out an alarming amount to start with. (You could ask at this point if it wasn't swapping out why add more memory, and you may well have a point)

As for application specific, the rp7410 and rp5470 are the database and apps tiers respectively of an Oracle E-Business Suite (11.5.10, OS is 11iv1.

[Patrick Wallek]

In order to use all of your RAM, you need to 1 of 2 things.

1) You need to have at least as much swap as you have RAM.

or

2) You need to set swapmemon=1 in the kernel (it requires a reboot if not set) and then have swap space equal to 25% of your RAM.

The reason for this is because when a process starts is reserves an amount of swap space just in case it needs it. If a process can't reserve the space it needs, then it will fail.