optimize oracle rdbms on vmware guy harrison director, r&d melbourne guy.harrison@quest.com...
Post on 15-Jan-2016
218 Views
Preview:
TRANSCRIPT
Optimize Oracle RDBMS on VMware
Guy HarrisonDirector, R&D Melbournewww.guyharrison.net Guy.harrison@quest.com@guyharrison
Introductions
Blue
Yellow
Red
0 10 20 30 40 50 60 70 80
Star trek shirt fatality analysis
Pct
11
©2011 Quest Software, Inc. All rights reserved..
Agenda
• Motivations for Virtualization
• VMware ESX resource management:
• Memory
• CPU
• IO
• Paravirtualization (OVM) vs Hardware Assisted
Virtualization (ESX)
• RAC on VMware
12
©2011 Quest Software, Inc. All rights reserved..
Motivations for Virtualization
• Better utilization of server resources• Reduced power consumption
Server Consolidation
• Fewer physical machines• Backup, cloning, rapid provisioningManageability
• Adjust resources on demand• A complement to the physical “grid”
visionElastic computing
13
©2011 Quest Software, Inc. All rights reserved..
Resistance to Database virtualization
• Virtual CPU & IO• Sharing of virtual resources Performance
• Large databases too big for a single VM
• RAC-style clustering problematic Scale
• Oracle’s stance often misunderstood
• See MyOracleSupport 249212.1Support
14
©2011 Quest Software, Inc. All rights reserved..
DB virtualization is happening
15
©2011 Quest Software, Inc. All rights reserved..
Oracle virtualization is lagging....
SQL Server
File and Print Servers
IIS
Active Directory
Apache
Exchange
Sharepoint
Java
Oracle
None of the Above
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Which of the following do you run in VMs?
Quest survey of vFoglight users , 2010
16
©2011 Quest Software, Inc. All rights reserved..
ESX Memory management
17
©2011 Quest Software, Inc. All rights reserved..
Managing ESX memory
• ESX can “overcommit” memory• Sum of all VM physical memory allocations > actual ESX physical memory
• Memory is critical to Oracle server performance• SGA memory to reduce datafile IO
• PGA memory to reduce sort & hash IO
• ESX uses four methods to share memory:• Memory Page Sharing
• Memory compression
• “Ballooning”
• ESX swapping
• DBA needs to carefully configure to avoid disaster
Configuring VM memory
Relative Memory Priority for this VM
Minimum Memory for this VM
VMs Compete for memory in this range
Maximum memory for the VM (dynamic)
19
©2011 Quest Software, Inc. All rights reserved..
Monitoring VM memory
ESX Swap
ESX virtual memory
ESX physical memory
VM VM virtual memory
ESX swap
Effective VM physical memory
ESX and VM memory
ESX Swap
ESX virtual memory
ESX physical memory
VM
Apparent VM physical memory
ESX swap
Effective VM physical memory
Vmmemctl
“balloon”
VM SwapVM Swap
ESX Ballooning
ESX Ballooning
As memory grows, ESX balloon driver (vmmemctl) forces VM to page out
memory to VM swapfile
ESX Ballooning
• Inside the VM, paging to the
swapfile is observed.
• The guest OS will determine
which pages are paged out
• If LOCK_SGA=TRUE, then the
SGA should not be paged.
ESX Swap
ESX virtual memory
ESX physical memory
ESX swap
ESX Swapping
VM virtual memory
VM
Effective VM physical memory
ESX Swap
ESX virtual memory
ESX physical memory
ESX swap
Apparent VM physical memory
VMEffective VM physical memory
ESX Swapping
ESX Swapping
ESX swaps out VM memory to ESX swapfile
ESX Swapping
• Within the VM, swapping cannot
be detected.
• ESX will determine which
memory pages go to disk
• Usually occurs when VMware
tools are not installed
• Even if LOCK_SGA=TRUE,
SGA memory might be on disk
Avoiding Ballooning and swapping
memory reservations help avoid ballooning or ESX
swapping
29
©2011 Quest Software, Inc. All rights reserved..
Ballooning vs. Swapping
Swingbench workload running on Oracle database – from VMWare whitepaper: http://www.vmware.com/files/pdf/perf-vsphere-memory_management.pdf
30
©2011 Quest Software, Inc. All rights reserved..
VMware memory recommendations
• Paging or swapping of PGA or SGA is almost always a Very Bad
ThingTM.
• Use memory reservations to avoid swapping or ballooning
• Install VMware tools to allow ballooning instead of swapping
• Set Memory reservation = PGA+SGA+process Overhead
• Be realistic about memory requirements:
• In physical machines, we are used to using all available memory
• In VM, use only the memory you need, freeing up memory for other VMs
• Oracle advisories (or Spotlight) can show you how much memory is
needed
• Reduce VM reservation and Oracle memory targets in tandem to
release memory
32
©2011 Quest Software, Inc. All rights reserved..
ESX CPU management
33
©2011 Quest Software, Inc. All rights reserved..
ESX CPU management
• If more virtual CPUs than ESX CPUs, then vCPUs will
sometimes wait for physical CPU
• Time “stops” inside the VM when this occurs
• For multi-CPU VMs, it’s (nearly) all or nothing.
• A vCPU can be in one of three states:• Associated with an ESX CPU but idle
• Associated with an ESX CPU and executing instructions
• Waiting for ESX CPU to become available
• Shares and reservations determine which VM wins access to
the ESX CPUs
Configuring VM CPU
VMs compete for CPU in this range
Shares determine relative CPU allocated when competing
CPU utilization VM
“CPU Ready” is the
amount of time VM
spends waiting on
ESX for CPU
Inside the VM, CPU
stats can be
misleading
SMP for vCPUs
• ESX usually has to
schedule all vCPUs for a
VM simultaneously
• The more CPUs the
harder this is
• Some CPU is also
needed for ESX
• More is therefore not
always better
(Thanks to Carl Bradshaw for letting me reprint this diagram from his Oracle on VMWare whitepaper)
37
©2011 Quest Software, Inc. All rights reserved..
ESX CPU performance comparisons
Vs 2 core 1.8 GHz physical machine
VT enabled
38
©2011 Quest Software, Inc. All rights reserved..
Programmatic performance
PLSQL
PLSQL compiled
Java Stored Proc
Simple C program
Standalone Java
0 5 10 15 20 25 30 35 40 45 50
ESX 2 VCPU 2.26 GHz VT enabled
ESX 2 CPU 3.5 GHz no-VT
Physical 2 CPU 1.8 GHz
Elapsed Time (s)
NB: Not a benchmark! Just some informal measurements!!
39
©2011 Quest Software, Inc. All rights reserved..
Programmatic performance (2)
ESX 2 CPU 3.5 GHz no-VT
ESX 2 VCPU 2.26 GHz VT enabled
0 50 100 150 200 250 300 350
333
72
Elapsed time Pct relative to Physical CPU adjusted for GHz
40
©2011 Quest Software, Inc. All rights reserved..
ESX CPU recommendations
• Use up to date chipsets and ESX software
• Allocate as few VCPUs as possible to each VM
• Use reservations and shares to prioritise access to ESX CPU
• Monitor ESX Ready time to determine the “penalty” of competing
with other virtual machines
41
©2011 Quest Software, Inc. All rights reserved..
ESX IO management
Typical VMWare disk configuration
IO Resource Allocation
• Disk shares can be used to prioritize IO bandwidth.
• This is poorly implemented prior to vSphere 4.1
44
©2011 Quest Software, Inc. All rights reserved..
Storage IO Control
• Prior to vSphere 4.1:• disk shares could be used only at the VM level, and only within a single
ESX host
• vSphere 4.1 Storage IO Control (SIOC):• Manages disk share priorities for all VMs attaching to the same
datastore
• Is triggered by high (“congested”) latency
• Can be enabled globally at the datastore level
• Enables equitable distribution even when set to defaults
Storage IO Control
46
©2011 Quest Software, Inc. All rights reserved..
vSphere 4.1 SIOC
47
©2011 Quest Software, Inc. All rights reserved..
SOIC won’t make up for a poorly configured IO layout
Performant VMware disk configuration
49
©2011 Quest Software, Inc. All rights reserved..
Optimal configuration
• See “Oracle Database Scalability in VMware® ESX” at
www.vmware.com/oracle
• Each virtual disk directly mapped via RDM to dedicated
RAID 0 (+1) group
41 Spindles!
50
©2011 Quest Software, Inc. All rights reserved..
ESX IO recommendations
• Follow normal best practice for physical disks
• Avoid sharing disk workloads • Dedicated datastores using VMFS
• Align virtual disks to physical disks?
• Consider Raw Device Mapping (RDM)
• Consider SIOC in vSphere 4.1
• If you can’t optimize IO, avoid IO:• Tune, tune, tune SQL
• Prefer indexed paths
• Memory configuration
• Don’t forget about temp IO (sorts, hash joins)
51
©2011 Quest Software, Inc. All rights reserved..
Shameless plugs
53
©2011 Quest Software, Inc. All rights reserved..
54
©2011 Quest Software, Inc. All rights reserved..
55
©2011 Quest Software, Inc. All rights reserved..
Paravirtualization vs Hardware Virtualization
56
©2011 Quest Software, Inc. All rights reserved..
Paravirtualization vs “Hardware Virtualization”
• Virtualization is not emulation....
• Where-ever possible, Hypervisor runs native code from
OS against underlying hardware
• Because a virtualized operating system is running
outside privileged x86 “ring 0”, direct calls to hardware
need special handling.
• The three main approaches are:• Full Virtualization (VMWare on older hardware)
• ParaVirtualization (Xen, Oracle VM)
• Hardware Assisted Virtualization (Intel VT, AMD-V)
Full virtualization
• Hardware calls from the VM
are handled by the
hypervisor by:• Catching the calls as they occur at
run time
• Re-writing the VM image at load
time (binary translation)
• Requires no special
hardware
• Supports any guest OS
• Relatively Poor performance
• Used by ESX on older chip-
sets
VM
Hypervisor
Hardware
Ring 0
Hardware Assisted virtualization
• Intel VT and AMD-V chips
add a non-root mode Ring
0.
• VM can issue instructions
from non-root Ring 0.
• CPU can divert these to
hypervisor
• No changes to OS required
• Good performance
• Requires modern chipsets
Hypervisor
Hardware
VM
Ring 0
Root Mode Non-Root Mode
Paravirtualization
• VM operating system is rewritten to translate device calls to “hypercalls”
• Hypercalls are handled by a special VM (dom0 in Xen/OVM)
• Good performance but requires modified VM OS
• Xen can use either paravirtualization or hardware assist
Hypervisor
Hardware
VM(domU)
Ring 0VM
(dom0)
60
©2011 Quest Software, Inc. All rights reserved..
RAC and ESX
61
©2011 Quest Software, Inc. All rights reserved..
Paravirtualization, ESX and RAC
• Prior to 11.2.0.2, Oracle relied on paravirtualized kernels to
maintain time synchronization for RAC clusters.
• From 11.2.0.2 Oracle uses Cluster Time Synchronization
Service (CTSS) to maintain clock sync, and this works on
ESX
• Therefore, Oracle supports RAC on Vmware ESX only from
11.2.0.2 onwards
• See Oracle MySupport Note 249212.1
62
©2011 Quest Software, Inc. All rights reserved..
References
• Latest version of this presentation:• http://www.slideshare.net/gharriso/optimize-oracle-on-vmware-5271530
• My blog (www.guyharrison.net ):• http://guyharrison.squarespace.com/blog/2010/2/22/memory-
management-for-oracle-databases-on-vmware-esx.html
• http://guyharrison.squarespace.com/blog/2010/4/9/esx-cpu-optimization-
for-oracle-databases.html
• http://guyharrison.squarespace.com/blog/2010/7/12/stolen-cpu-on-xen-
based-virtual-machines.html
• http://www.vmware.com/files/pdf/perf-vsphere-memory_management.pdf
• http://www.vmware.com/files/pdf/Oracle_Databases_on_vSphere_Deployment_Tips.pdf
• http://www.vmware.com/files/pdf/techpaper/VMW-vSphere41-SIOC.pdf
COLLABORATE 12April 22-26, 2012
Mandalay Bay Convention CenterLas Vegas, Nevada, USA
www.collaborate12.orgwww.collaborate12.ioug.org
top related