Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: 10g Memory Usage: 12 GB RAM & 5000 Connections ~ Need help understanding

Re: 10g Memory Usage: 12 GB RAM & 5000 Connections ~ Need help understanding

From: hpuxrac <johnbhurley_at_sbcglobal.net>
Date: 28 Jun 2006 10:29:50 -0700
Message-ID: <1151515790.068656.74660@b68g2000cwa.googlegroups.com>

DragonWoman wrote:
> Hello everyone,
>
> I'm looking for a little help explaining what's going on with my Oracle
> memory usage. Here are the details:
>
> MS Server 2003 R2 x64
> Oracle 10g (64-bit)
> 12 GB physical RAM
> SGA_MAX = 10G
> SGA_TARGET = 8G
> Auto Memory Management ON
> Shared server connections
>
> Here is what I am seeing. On startup, with no external connections
> (using Perf Mon):
>
> Private Bytes: 10.48 GB
> Page File Bytes: 10.48 GB
> Working Set: 0.22 GB
> Virtual Bytes: 10.74 GB
>
> So, I'm seeing all the SGA_MAX plus a few other things (PGA?) being
> allocated and reserved (Private Bytes). Working set is small because
> not much has happened yet.
>
> I gradually ramped up to 5,000 connections over a couple of hours and
> let it run for a while. Using Perf Mon, I monitored the CPU and memory
> usage for 17 hours and see the following:
>
> Private Bytes: 11.87 GB (Average) (Min: 11.11G, Max: 12.27G)
> Page File Bytes: 11.87 GB (Average) (Min: 11.11G, Max: 12.27G)
> Working Set: 0.92 GB (Average) (Min: 0.44G, Max: 1.18G)
> Virtual Bytes: 12.24 GB (Average) (Min: 11.48G, Max: 12.68G)
>
> The Auto Memory Tuning works like a charm, adjusting the large pool to
> allow for the number of connections. Max UGA per connection works out
> to 317 KB.
>
> I guess I need someone to explain to me why the private bytes grows. I
> mean, MAX_SGA is 10G, but when I check, the ASMM balances the SGA so
> that even though the shared and large pools have grown, the buffer
> cache has shrunk and it's still within 8 GB. So, that's 2 GB it's
> reserved for SGA, but not using. Using shared server, PGA isn't that
> big. So, why does the private bytes start at 10.5G and get up to
> 12.3G? I see the reading for "Page File" follows the Private Bytes
> exactly.
>
> I used Pslist (from sysinternals) just now and it lists VM and Private
> VM as 4 GB for Oracle.exe.

If you take 8 gig for SGA and 4 gig for memory for oracle.exe doesn't that get you up to your 12 gig?

Many people with servers that have this much RAM might consider supporting 5000 connections with dedicated server.

> I don't see a lot of swapping. Available memory doesn't get below 60
> MB, pagefile usage is around 30%. Buffer cache hit ratio is 99.99%.

A lot of swapping?

Sorry we don't run windows here for oracle but wouldn't you want a higher number for available memory on a machine that has this much memory?

Current oracle performance tuning thinking discounts the useability of cache hit ratios but one that is that high makes me wonder if you have way too much memory devoted to it. If you cut your buffer cache down by 50% do you still get 99.9 percent? Received on Wed Jun 28 2006 - 12:29:50 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US