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: excessive swapping during rman backups on Linux 2.6

Re: excessive swapping during rman backups on Linux 2.6

From: DA Morgan <damorgan_at_psoug.org>
Date: Mon, 15 Jan 2007 10:48:05 -0800
Message-ID: <1168886883.380647@bubbleator.drizzle.com>


NetComrade wrote:
> We have a customer that recently have migrated to Linux from Windows.
> The database is 9.2.7.the os is redhat 4.0 We noticed that whenever
> there is a level 0 backup running, the machine starts swapping, load
> jumps, and it becomes unresponsive at times. The db has a 'max sga'
> set at 3G and a pga_target of 500m. The machine has 8G of ram (one db
> on the machine, small data processing app). The number of connections
> is around a hundred.. ---There should be enough memory resources for
> this db
>
> There is a metalink note 360402.1 describing out situation, and it
> basically suggests adjusting some kernel settings to make kernel
> reserve less memory for FS caching. Unfortunately, these parameters
> (/proc/sys/vm/pagecache, /proc/sys/vm/freepages /proc/sys/vm/buffermem
> no longer exist in kernel 2.6 ). Besides going 'directio' (customer
> had mixed results during testing), any other suggestion(s)?
>
> sar output during levl0:
> kernel.sem = 1000 32000 100 128
> 11:40:02 PM 96.67 108.06
> 11:50:08 PM 145.22 62.10
> Average: 1.96 1.20
> 12:00:01 AM pswpin/s pswpout/s
> 12:10:05 AM 269.83 176.13
> 12:20:01 AM 462.24 142.03
> 12:30:22 AM 259.53 108.06
> 12:40:12 AM 283.60 132.79
> 12:50:01 AM 343.39 88.04
> 01:00:01 AM 352.47 152.02
> 01:10:01 AM 460.48 218.64
> 01:20:03 AM 215.97 99.27
> 01:30:01 AM 305.85 105.11
> 01:40:02 AM 232.30 112.40
> 01:50:02 AM 327.64 131.49
> 02:00:01 AM 247.68 88.48
> 02:10:03 AM 157.55 67.92
> 02:20:05 AM 223.74 90.92
> 02:30:01 AM 129.21 44.13
> 02:40:02 AM 140.25 61.81
> 02:50:01 AM 17.83 0.00
> 03:00:01 AM 15.00 0.33
> 03:10:01 AM 3.73 0.00
> 03:20:01 AM 2.75 0.00
> 03:30:01 AM 1.02 0.00
> 03:40:01 AM 0.70 0.00
> 03:50:01 AM 0.38 0.00
> 04:00:01 AM 0.89 0.00
> 04:10:01 AM 34.69 0.00
>
> # free
> total used free shared buffers
> cached
> Mem: 8165948 8148012 17936 0 4016
> 1109552
> -/+ buffers/cache: 7034444 1131504
> Swap: 16779884 1224096 15555788
>
> sysctl:
> fs.file-max = 65536
> kernel.shmall = 1572864
> kernel.sem = 1000 32000 100 128
> kernel.shmmax = 6442450944
> net.ipv4.ip_local_port_range = 1024 65000
> vm.nr_hugepages=3100
>
> .......
> We run Oracle 9iR2,10gR1/2 on RH4/RH3 and Solaris 10 (Sparc)
> remove NSPAM to email

Run the following as root

/sbin/sysctl -p

and compare with Oracle's recommendations which will be something close to this:

fs.file-max = 65536

kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.core.rmem_default = 1048576
net.core.rmem_max = 1048576
net.core.wmem_default = 262144
net.core.wmem_max = 262144
net.ipv4.ip_forward = 0

net.ipv4.conf.default.rp_filter = 1
net.ipv4.ip_local_port_range = 1024 65000
-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org
Received on Mon Jan 15 2007 - 12:48:05 CST

Original text of this message

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