Xen server 6.1 technical sales presentation

XenServer 6.1 Technical Overview
September 2012

What’s so Great About Xen?

• It’s robust
ᵒNative 64-bit hypervisor
ᵒRuns on bare metal
ᵒDirectly leverages CPU hardware for virtualization
• It’s widely-deployed
ᵒTens of thousands of organizations have deployed Xen
• It’s advanced
ᵒOptimized for hardware-assisted virtualization and paravirtualization
• It’s trusted
ᵒOpen, resilient Xen security framework
• It’s part of mainline Linux

© 2012 Citrix | Confidential – Do Not Distribute

Understanding Architectural Components

The Xen hypervisor and control domain (dom0) manage physical server
resources among virtual machines


Understanding the Domain 0 Component

Domain 0 is a compact specialized Linux VM that manages the network and
storage I/O of all guest VMs … and isn’t the XenServer hypervisor


Understanding the Linux VM Component

Linux VMs include paravirtualized kernels and drivers, and Xen is part of
Mainline Linux 3.0


Understanding the Windows VM Component

Windows VMs use paravirtualized drivers to access storage and network
resources through Domain 0


XenServer Meets All Virtualization Needs
• High performance, resilient virtualization platform
Enterprise
• Simple deployment and management model
Data Center • Host based licensing to control CAPEX

Desktop • Optimized for high performance desktop workloads
Virtualization • Storage optimizations to control VDI CAPEX

Cloud • Platform for IaaS and Cloud Service Providers
• Powers the NetScaler SDX platform
Infrastructure • Fully supports Software Defined Networking


Enterprise
Data Center Virtualization

XenCenter – Simple XenServer Management

• Single pane of management glass
• Manage XenServer hosts
ᵒ Start/Stop VMs
• Manage XenServer resource pools
ᵒ Shared storage
ᵒ Shared networking
• Configure advanced features
ᵒ HA, WLB, Reporting, Alerting
• Configure updates


Management Architecture Comparison
“The Other Guys” Citrix XenServer

Traditional Management Distributed
Architecture Management Architecture
Single backend management server Clustered management layer


Role-Based Administration

• Provide user roles with varying permissions
• Pool Admin
• Pool Operator
• VM Power Admin
• VM Admin
• VM Operator
• Read-only
• Roles are defined within a Resource Pool

• Assigned to Active Directory users, groups

• Audit logging via Workload Reports


XenMotion Live VM Migration

Shared Storage
More about XenMotion


Live Storage XenMotion

Live • Migrates VM disks from any
Virtual
Machine
storage type to any other
storage type
ᵒLocal, DAS, iSCSI, FC
XenServer Hypervisor • Supports cross pool migration
ᵒRequires compatible CPUs
VDI(s) • Encrypted Migration model
• Specify management interface
for optimal performance
XenServer Pool

More about Storage XenMotion


Heterogeneous Resource Pools

Virtual Machine
Safe Live Migrations

Mixed Processor Pools

Feature Feature Feature Feature Feature Feature Feature Feature
1 2 3 4 1 2 3 4

Older CPU Newer CPU

XenServer 1 XenServer 2


Memory Overcommit

• Feature name: Dynamic Memory
Control
• Ability to over-commit RAM
resources
• VMs operate in a compressed or
balanced mode within set range
• Allow memory settings to be
adjusted while VM is running
• Can increase number of VMs per
host


Virtual Appliances (vApp)

• Support for “vApps” or Virtual
Appliances
ᵒOVF definition of Virtual Appliance
• vApp contains one or more Virtual
Machines
• Enables grouping of VMs which can
be utilized by
ᵒXenCenter
ᵒIntegrated Site Recovery
ᵒAppliance Import and Export
ᵒHA


Virtual Machine Protection and Recovery

• Policy based snapshotting and
archiving
• Separate scheduling options for
snapshot and archive
ᵒSnapshot-only or Snapshot and Archive
• Policy Configuration
ᵒAdd multiple VMs to policy
ᵒSearch filter available
ᵒVM can only belong to 1 policy
ᵒXenCenter or CLI


High Availability in XenServer

• Automatically monitors hosts and
VMs
• Easily configured within XenCenter
• Relies on Shared Storage
ᵒiSCSI, NFS, HBA

• Reports failure capacity for DR
planning purposes

More about HA


Advanced Data Center
Automation

Optimizing Storage – Integrated StorageLink

Virtualization can hinder the linkage
XenServer between servers and storage, turning
Hosts
expensive storage systems into little
more than “dumb disks”

Citrix StorageLink™ technology lets your
XenServer StorageLink virtual servers fully leverage all the
Hosts Storage
power of existing storage systems

More about StorageLink


Workload Placement Services

• Feature name: Workload Balancing
• Automated guest start-up and
management based on defined
policy
• Guests automatically migrate from
one host to another based on
resource usage
• Power-on/off hosts as needed
• Report on utilization of pool
resources – by VM, by host, etc.
More about WLB


Integrated Site Recovery

• Supports LVM SRs
• Replication/mirroring setup outside
scope of solution
ᵒFollow vendor instructions
ᵒBreaking of replication/mirror also manual
• Works with every iSCSI and FC
array on HCL
• Supports active-active DR

More about Site Recovery


Delegated Web Based Administration

• Enables:
• IT delegation for administrators
• VM level administration for end users
• Support for multiple pools
• Active Directory enabled
• XenVNC and RDP console access


Live Memory Snapshot and Rollback

• Live VM snapshot and revert
ᵒBoth memory and disk state are
captured
ᵒOptional quiesce option via VSS
provider (Windows guests)
ᵒOne-click revert
• Snapshot branches
ᵒSupport for parallel subsequent
checkpoints based on a previous
common snapshot


Supporting High Performance Graphics

• Feature name: GPU pass-through
• Enables high-end graphics in VDI
deployments with HDX 3D Pro
• Optimal CAD application support
with XenDesktop
• More powerful than RemoteFX,
virtual GPUs, or other general
purpose graphics solutions


Benefits of GPU Pass-through

Without GPU pass-through, each user With GPU pass-through, hardware
requires their own Blade PC costs are cut up to 75%

GPU cards

XenServer Host

More about GPU Pass Through


Controlling Shared Storage Costs – IntelliCache

• Caching of XenDesktop 5 images
• Leverages local storage
• Reduce IOPS on shared storage
• Supported since XenServer 5.6 SP2


IntelliCache Fundamentals
XenDesktop 1. Master Image created through
XenDesktop MCS
2. VM is configured to use Master Image
3. VM using Master Image is started

001
011
4. XenServer creates read cache object
on local storage

0101
0011
5. Reads in VM being done from local
cache
6. Additional Reads done from SAN
when required
7. Writes will happen in VHD child per
VM
8. Local “write” cache is deleted when
0101
0011

Master Image
Cache VM is shutdown/restarted
9. Additional VMs will use same read
cache
NFS Based Storage

Cost Effective VM Densities
• Supporting VMs with up to:
ᵒ16 vCPU per VM
ᵒ128GB Memory per VM
• Supporting XenServer hosts with up to:
ᵒ1TB Physical RAM
ᵒ160 logical processors
• Yielding up to 150 Desktop images per host

• Included at no cost with all XenDesktop purchases

• Cisco Validated Design for XenDesktop on UCS


Distributed Virtual Network Switching

• Virtual Switch VM

ᵒOpen source: www.openvswitch.org
ᵒProvides a rich layer 2 feature set
ᵒCross host internal networks VM

ᵒRich traffic monitoring options
ᵒovs 1.4 compliant

• DVS Controller
ᵒVirtual appliance
VM

ᵒWeb-based GUI VM

ᵒCan manage multiple pools
ᵒCan exist within pool it manages VM


Switch Policies and Live Migration
Windows VM
•Allow
Windows VM all traffic VM
SAP •Allow all traffic
VM
•Allow only SAP traffic
Linux VM
•RSPAN to VLAN 26
•Allow SSH on eth0
Linux VM HTTP on eth1
•Allow
•Allow SSH on eth0 VM

•Allow HTTP on eth1

Linux VM1
Linux •Allow all traffic
VM1
Linux •Allow all traffic
VM2 VM

Linux •Allow SSH on eth0
VM2
•Allow SSH on eth0
•Allow HTTP on eth1 VM
•Allow HTTP on eth1
Windows VM
Windows VM
•Allow RDP and deny HTTP
SAP VM•Allow RDP and deny HTTP VM

•Allow only SAP traffic
•RSPAN to VLAN 26 More about DVSC


Single Root IO Virtualization (SR-IOV)
Guest Guest
App VM App VM
• PCI Specification for direct IO access
ᵒHardware supports multiple PCI ids
VF driver VF driver
ᵒPresents multiple virtual NICs from single NIC
• Virtual NICs presented directly into guests
dom0
ᵒMinimize hypervisor overhead in high
performance networks
vSwitch

• Not without downsides Physical
driver

ᵒRequires specialized hardware
Virtual NIC Virtual NIC NIC
ᵒCan not participate in DVS
ᵒDoes not support live migration
ᵒLimited number of virtual NICs
More about SRIOV


NetScaler SDX – Powered by XenServer

• Complete tenant isolation
• Complete independence
• Partitions within instances
• Optimized network: 50+ Gbps
• Runs default XenServer 6


Support for SCVMM

• SCVMM communicates with CIMOM
in XenServer which communicates
with XAPI
• Requires SCVMM 2012
• Very easy to setup
ᵒDelivered as Integration Suite
Supplemental Pack
ᵒAdd Resource Pool or host
• Secure communication using
certificates


Support for SCOM

• Monitor XenServer hosts through System
Center Operations Manager
• Support for SCOM 2007 R2 and higher
• Part of Integration Suite Supplemental Pack
• Monitor various host information (considered
Linux host)
ᵒMemory usage
ᵒProcess information
ᵒHealth status


Summary of Key Features and Packages
• Integrated disaster recovery management
• Provisioning services for physical and virtual workloads

• Dynamic Workload Balancing and Power Management
• Web Management Console with Delegated Admin
• Monitoring pack for Systems Center Ops Manager

• High Availability
• Dynamic Memory Control
• Shared nothing live storage migration

• Resource pooling with shared storage
• Centralized management console
• No performance restrictions


vSphere 5.1 and XenServer 6.1 Quick Comparison
Feature XenServer Edition vSphere Edition
Hypervisor high availability Advanced Standard
NetFlow Advanced Enterprise Plus
Centralized network management Free Enterprise Plus
Distributed virtual network switching Advanced Enterprise Plus with Cisco Nexus 1000v
Storage live migration Advanced Standard
Serial port aggregation Not Available Standard
Network based resource scheduling Enterprise Not Available
Disk IO based resource scheduling Enterprise Not Available
Optimized for desktop workloads Yes Desktop Edition is repackaged
Enterprise Plus
Licensing Host based Processor based


XenServer 6.1 – Product Edition Feature Matrix
Feature Free Advanced Enterprise Platinum
64-bit Xen Hypervisor a a a a
Active Directory Integration a a a a
VM Conversion Utilities a a a a
Live VM Migration with XenMotion™ a a a a
Multi-Server Management with XenCenter a a a a
Management Integration with Systems Center VMM a a a a
Automated VM Protection and Recovery a a a
Live Storage Migration with Storage XenMotion™ a a a
Distributed Virtual Switching a a a
Dynamic Memory Control a a a
High Availability a a a
Performance Reporting and Alerting a a a
Mixed Resource Pools with CPU Masking a a a
Dynamic Workload Balancing and Power Management a a
GPU Pass-Through for Desktop Graphics Processing a a
IntelliCache™ for XenDesktop Storage Optimization a a
Live Memory Snapshot and Revert a a
Provisioning Services for Virtual Servers a a
Role-Based Administration and Audit Trail a a
StorageLink™ Advanced Storage Management a a
Monitoring Pack for Systems Center Ops Manager a a
Web Management Console with Delegated Admin a a
Provisioning Services for Physical Servers a
Site Recovery a
Price Free $1000/server $2500/server $5000/server

Subscription Advantage
Citrix Subscription Advantage entitles customers the ability to upgrade to the latest software version for their product
at no additional charge. Support not included.
Renewal Categories
Current:
Renewal SRP
Active memberships

Reinstatement: Renewal SRP + pro-rated renewal for time expired
Memberships that are expired 1 through 365 days + 20% fee

Recovery:
Recovery SRP
Memberships that are expired more than 365 days
Edition Renewal SRP Recovery SRP
XenServer Platinum $675.00 per SVR $2,800.00 per SVR
XenServer Enterprise $325.00 per SVR $1,400.00 per SVR
XenServer Advanced $130.00 per SVR $560.00 per SVR


Support Options
XenServer Support Options Premier Support
Cost 7% of license cost (SRP)
Product Coverage XenServer Advanced, Enterprise and Platinum
Coverage Hours 24x7x365
Incidents Unlimited
Named Contacts Unlimited
Type of Access Phone/Web/Email
Add-on Service Options
Software or Hardware TRM 200 hours/Unlimited incidents/1region $40,000
Additional TRM hours 100 hours $20,000
Fully Dedicated TRM 1600 hours/Unlimited incidents/1 region $325,000
On-site Days On-site technical support service $2,000 per day
Assigned Escalation 200 hours/1 region (must have TRM) $16,000
Fully Dedicated Assigned Escalation 1600 hours $480,000


It’s Your Budget … Spend it Wisely

• Vendor lock-in great for vendor
Single Vendor • Beware product lifecycles and tool set changes

• ROI Calculators always show vendor author as best
ROI Can be Manipulated • Use your own numbers

• Over buying is costly; get what you need
Understand Support Model • Support call priority with tiered models

• Some projects have requirements best suited to specific tool
Use Correct Tool • Understand deployment and licensing impact

Leverage Costly Features as • Blanket purchases benefit only vendor
Required • Chargeback to project for feature requirements


How GPU Pass-through Works

• Identical GPUs in a host auto-create a GPU
group
• The GPU Group can be assigned to set of
VMs – each VM will attach to a GPU at VM
boottime
• When all GPUs in a group are in use,
additional VMs requiring GPUs will not start
• GPU and non-GPU VMs can (and should)
be mixed on a host
• GPU groups are recognized within a pool
ᵒIf Server 1, 2, 3 each have GPU type 1, then
VMs requiring GPU type 1 can be started on
any of those servers


GPU Pass-through HCL is Server Specific

• Server
ᵒHP ProLiant WS460c G6 Workstation series*
ᵒIBM System x3650 M3
ᵒDell Precision R5500
• GPU (1-4 per host)
ᵒNVIDIA Quadro 2000, 4000, 5000, 6000
ᵒNVIDIA Tesla M2070-Q
• Support for Windows guests only
• Important: Combinations of servers +
GPUs must be tested as a pair


Limitations of GPU Pass-through

• GPU Pass-through binds the VM to host for duration of session
ᵒRestricts XenMotion and WLB
• Multiple GPU types can exist in a single server
ᵒE.g. high performance and mid performance GPUs
• VNC will be disabled, so RDP is required
• Fully supported for XenDesktop, best effort for other windows workloads
ᵒNot supported for Linux guests
• HCL is very important


Enabling IntelliCache on XenServer Hosts

• IntelliCache requires local EXT3 storage, to be selected during XenServer
installation
• If this is selected during installation the host is automatically enabled for
IntelliCache
• Manual steps in Admin guide


Enabling IntelliCache in XenDesktop

• http://support.citrix.com/
article/CTX129052
• Use IntelliCache checkbox when
adding a host in Desktop Studio
• Supported from XenDesktop 5 FP1


NFS Ops

10000
12000
14000
16000
18000

4000
6000
8000

2000

0
0:00:00
0:00:45
0:01:30
0:02:15
0:03:00
0:03:45
0:04:30
0:05:15
0:06:00
0:06:45
0:07:30
0:08:15
0:09:00
0:09:45
0:10:30
0:11:15

0:12:00
0:12:45
0:13:30
0:14:15
0:15:00
0:15:45
0:16:30
0:17:15
0:18:00
0:18:45
0:19:30
0:20:15
NFS Read Ops
0:21:00
0:21:45
0:22:30
0:23:15
0:24:00
NFS Ops (Non-IC)

0:24:45
0:25:30
NFS Write Ops

0:26:15
0:27:00
0:27:45
0:28:30
0:29:15
0:30:00
0:30:45
0:31:30
0:32:15
IOPS – 1000 Users – No IntelliCache

0:33:00
0:33:45
0:34:30
0:35:15
0:36:00
0:36:45
0:37:30
0:38:15
0:39:00
0:39:45
0:40:30
0:41:15
0:42:00
0:42:45
0:43:30
0:44:15
0:45:00
0:45:45

NFS Ops

1000
1500
2000
2500
3000

500

0
0:00:00
0:00:40
0:01:20
0:02:00
0:02:40
0:03:20
0:04:00
0:04:40
0:05:20
0:06:00
0:06:40
0:07:20
0:08:00
0:08:40
0:09:20
0:10:00

0:10:40
0:11:20
0:12:00
0:12:40
0:13:20
0:14:00
0:14:40
0:15:20
0:16:00
0:16:40
0:17:20
0:18:00
0:18:40
NFS Read Ops
0:19:20
0:20:00
0:20:40
0:21:20
0:22:00
0:22:40
0:23:20
NFS Ops (Cold Cache)

NFS Write Ops

0:24:00
0:24:40
0:25:20
0:26:00
0:26:40
0:27:20
0:28:00
0:28:40
0:29:20
0:30:00
0:30:40
0:31:20
IOPS – 1000 Users – Cold Cache Boot

0:32:00
0:32:40
0:33:20
0:34:00
0:34:40
0:35:20
0:36:00
0:36:40
0:37:20
0:38:00
0:38:40
0:39:20
0:40:00
0:40:40
0:41:20

NFS Ops

10
15
20
25
35

30

0
5
0:00:00
0:00:45
0:01:30
0:02:15
0:03:00
0:03:45
0:04:30
0:05:15
0:06:00
0:06:45
0:07:30
0:08:15
0:09:00
0:09:45
0:10:30
0:11:15

0:12:00
0:12:45
0:13:30
0:14:15
0:15:00
0:15:45
0:16:30
0:17:15
0:18:00
0:18:45
0:19:30
0:20:15
NFS Read Ops 0:21:00
0:21:45
0:22:30
0:23:15
0:24:00
0:24:45
NFS Ops (Hot Cache)

0:25:30
NFS Write Ops

0:26:15
0:27:00
0:27:45
0:28:30
0:29:15
0:30:00
0:30:45
0:31:30
0:32:15
0:33:00
IOPS – 1000 Users – Hot Cache Boot

0:33:45
0:34:30
0:35:15
0:36:00
0:36:45
0:37:30
0:38:15
0:39:00
0:39:45
0:40:30
0:41:15
0:42:00
0:42:45
0:43:30
0:44:15
0:45:00

Limitations of IntelliCache

• Best results achieved with local SSD drives
ᵒSAS and SATA supported, but spindled disks are slower
• XenMotion and WLB restrictions (pooled images)
• Best practice Local space sizing
ᵒExpecting 50% cache usage per user + daily log off
ᵒ[real size master image] + #[users per server] * [size master image] * 0,5
ᵒCache disk may vary according to VM lifecycle definition (reboot cycle)


IntelliCache Conclusions

• Dramatic reduction of I/O for pooled desktops
• Significant reduction of I/O for assigned desktops
ᵒStill need IOPS for write traffic
ᵒLocal write cache benefits
• Storage investment much lower – and more appropriate
• Overall TCO 15 – 30 % improvement
• Continued evolution of features to yield better performance and TCO


Components
Analysis Engine service

• Workload Balancing Components
ᵒData Collection Manager service
ᵒAnalysis Engine service Data Store
ᵒWeb Service Host

Resource Pool
XenServer
ᵒData Store
ᵒXenServer
ᵒXenCenter

XenCenter Data Collection
Manager service

Resource Pool
XenServer
Recommendations

Web Service Host


Placement Strategies

• Maximize Performance
ᵒDefault setting
ᵒSpread workload evenly across all
physical hosts in a resource pool
ᵒThe goal is to minimize
CPU, memory, and network pressure for
all hosts
• Maximize Density
ᵒFit as many virtual machines as
possible onto a physical host
ᵒThe goal is to minimize the number of
physical hosts that must be online


Critical Thresholds

• Components included in WLB
evaluation:
ᵒCPU
ᵒMemory
ᵒNetwork Read
ᵒNetwork Write
ᵒDisc Read
ᵒDisk Write
• Optimization recommendation is
being triggered if a threshold is
reached


Reports

• Pool Health
ᵒShows aggregated resource usage for a pool. Helps you evaluate the effectiveness of
your optimization thresholds
• Pool Health History
ᵒDisplays resource usage for a pool over time. Helps you evaluate the effectiveness of
your optimization thresholds
• Host Health History
ᵒSimilar to Pool Health History but filtered by a specific host
• Optimization Performance History
ᵒShows resource usage before and after executing optimization recommendations


Reports

• Virtual Machine Motion History
ᵒProvides information about how many times virtual machines moved on a resource
pool, including the name of the virtual machine that moved, number of times it
moved, and physical hosts affected
• Optimization Performance History
ᵒShows resource usage before and after executing accepting optimization
recommendations
• Virtual Machine Performance History
ᵒDisplays key performance metrics for all virtual machines that operated on a host during
the specified timeframe


Workload Chargeback Reports

• Billing codes and costs
• Resources to be charged
• Exportable data


Workload Balancing Virtual Appliance

• Ready-to-use WLB Virtual Appliance
• Up and running with WLB in minutes
rather than hours
• Small footprint, Linux Virtual
Appliance
ᵒ~150Mb


Installation

• Download Virtual Appliance
• Import Virtual Appliance
• Start Virtual Appliance
• Initial setup steps
ᵒDefine steps
• Enable WLB in XenCenter


Details


• Replaces StorageLink Gateway Site
Recovery
• Decoupled from StorageLink adapters
• Supports LVM SRs only in this release
• Replication/mirroring setup outside
scope of solution
ᵒFollow vendor instructions
ᵒBreaking of replication/mirror also manual
• Works with every iSCSI and FC array on
HCL
• Supports active-active DR


Feature Set

• Integrated in XenServer and XenCenter
• Support failover and failback
• Supports grouping and startup order through vApp functionality
• Failover pre-checks
ᵒPowerstate of source VM
ᵒDuplicate VMs on target pool
ᵒSR connectivity
• Ability to start VMs paused (e.g. for dry-run)


How it Works

• Depends on “Portable SR” technology
ᵒDifferent from Metadata backup/restore functionality
• Creates a logical volume on SR during setup
• Logical Volume contains
ᵒSR metadata information
ᵒVDI metadata information for all VDIs stored on SR
• Metadata information is read during failover sr-probe


Integrated Site Recovery - Screenshots


Distributed Virtual Switch
Details

Terminology

• OpenFlow
ᵒAn open standard that separates the control and data paths for switching devices
• OpenFlow switch
ᵒCould be physical or virtual
ᵒIncludes packet processing and remote configuration/control support via OpenFlow
• Open vSwitch
ᵒAn OSS Linux-based implementation of an OpenFlow virtual switch
ᵒMaintained at www.openvswitch.org
• vSwitch Controller
ᵒA commercial implementation of a OpenFlow controller
ᵒProvides integration with XenServer pools


Core Distributed Switch Objectives

• Extend network management to virtual networks
• Provide network monitoring using standard protocols
• Define network policies on virtual objects
• Support multi-tenant virtual data centers
• Provide cross host private networking without VLANs
• Answer to VMware VDS and Cisco Nexus 1000v


Understanding Policies

• Access control VM

ᵒBasic Layer 3 firewall rules
ᵒDefinable by pool/network/VM
ᵒInheritance controls VM

VM

VM

VM




• QoS
ᵒRate limits to control bandwidth VM

VM

VM

VM




• QoS
• RSPAN VM

ᵒTransparent monitoring of VM level
traffic

VM

VM

VM


What is NetFlow?

• Layer 3 monitoring protocol
• UDP/SCTP based
• Broadly adopted solution
• Implemented in three parts
ᵒExporter (DVS)
ᵒCollector
ᵒAnalyzer
• DVSC is NetFlow v5 based
ᵒEnabled at pool level


Performance Monitoring

• Enabled via NetFlow
• Dashboard
ᵒThroughput
ᵒPacket flow
ᵒConnection flow
• Flow Statistics
ᵒSlice and dice reports
ᵒSee top VM traffic
ᵒData goes back 1 week


Bonus Features *****

• Jumbo Frames
• Cross Server Private Networks
• LACP
• 4 NIC bonds


Protecting Workloads

• Not just for mission critical
applications anymore
• Helps manage VM density issues
• "Virtual" definition of HA a little
different than physical
• Low cost / complexity option to
restart machines in case of failure


High Availability Operation

• Pool-wide settings
• Failure capacity – number of hosts to
carry out HA Plan
• Uses network and storage heartbeat
to verify servers


VM Protection Options

• Restart Priority
ᵒDo not restart
ᵒRestart if possible
ᵒRestart
• Start Order
ᵒDefines a sequence and delay to ensure applications run correctly


HA Design – Hot Spares

Simple Design
ᵒ Similar to hot spare in disk array
ᵒ Guaranteed available
ᵒ Inefficient  Idle resources
Failure Planning
ᵒ If surviving hosts are fully loaded – VMs will be forced to start on spare
ᵒ Could lead to restart delays due to resource plugs
ᵒ Could lead to performance issues if spare is pool master
ᵒ If using WLB, need to exclude spare from rebalancing


HA Design – Distributed Capacity

Efficient Design
ᵒAll hosts utilized
ᵒWLB can ensure optimal performance
Failure Planning
ᵒImpacted VMs automatically placed for best fit
ᵒRunning VMs undisturbed
ᵒProvides efficient guaranteed availability


HA Design – Impact of Dynamic Memory

Enhances Failure Planning
ᵒDefine reduced memory which meets SLA
ᵒOn restart, some VMs may “squeeze” their memory
ᵒIncreases host efficiency


HA Design - Preventing Single Point of Failure

• HA recovery may create single points of failure
• WLB host exclusion minimizes impact


HA Enhancements in XenServer 6

• HA over NFS
• HA with Application Packages
ᵒDefine multi-VM services
ᵒDefine VM startup order and delays
ᵒApplication packages can be defined from
running VMs

• Auto-Start VMs are removed
ᵒUsage conflicted with HA failure planning
ᵒCreated situations when perceived host
recovery wasn’t met


High Availability – No Excuses

• Shared storage the hardest part of setup
ᵒSimple wizard can have HA defined in minutes
ᵒMinimally invasive technology
• Protects your important workloads
ᵒReduce on-call support incidents
ᵒAddresses VM density risks
ᵒNo performance, workload, configuration penalties
• Compatible with resilient application designs
• Fault tolerant options exist through ecosystem


Leverage Array Technologies

• No file system overlay Array OS Array OS
• Use Best-of-Breed technologies
ᵒThin Provisioning Hypervisor Filesystem
Snapshotting Snapshotting
Provisioning Provisioning
ᵒDeduplexing Snapshotting
Cloning Cloning
ᵒCloning Provisioning
Cloning
ᵒSnapshotting
ᵒMirroring VM VM VM VM VM VM VM VM VM VM

• Maximize array performance VM VM VM VM VM VM VM VM VM VM

Traditional Approach Citrix StorageLink


No StorageLink – Inefficient LUN Usage
Today 4 weeks 8 weeks 12 weeks

Customer request Customer adds 5 VMs Customer adds 5 VMs Customer adds 5 VMs
for 600GB with 50 GB each with 50 GB each with 50 GB each
LUN 600GB

Customer
400 GB free 400 GB free 400 GB free requests
new
storage
LUN 600GB LUN 600GB LUN 600GB LUN 600GB capacity
50GB disk 50GB disk
50GB disk 50GB disk
50GB disk 50GB disk
50GB disk 50GB disk
50GB disk 50GB disk
50GB disk 50GB disk 50GB disk

1 TB storage capacity


With StorageLink – Maximize Array Utilization
Today 4 weeks 8 weeks 12 weeks

Customer request Customer adds 5 VMs Customer adds 5 VMs Customer adds 5 VMs
for 600 GB with 50 GB each with 50 GB each with 50 GB each

1 TB free 750 GB free 500 GB free 250 GB free

50GB LUN
50GB LUN
50GB LUN
50GB LUN
50GB LUN
50GB LUN 50GB LUN
50GB LUN 50GB LUN
50GB LUN 50GB LUN
50GB LUN 50GB LUN
50GB LUN 50GB LUN
50GB LUN 50GB LUN 50GB LUN

1 2012 Citrix Confidential – Do Not Distribute
© TB storage |capacity

StorageLink – Efficient Snapshot Management
NO StorageLink With StorageLink

VM Snapshot capacity limited to LUN VM Snapshot capacity limited storage
size pool size

400 GB free
750 GB free

Snapshot capacity
LUN 600GB
350 GB
750 GB

50GB disk
50GB disk 50GB LUN
50GB disk 50GB LUN
50GB disk 50GB LUN
50GB disk 50GB LUN
50GB LUN


Integrated StorageLink Architecture

XenServer Host

XAPI Daemon

SMAPI

CSLG
LVM NFS NetApp …
Bridge

EQL NTAP SMI-S …


Network Performance for GbE with PV drivers

• XenServer PV drivers can sustain peak throughput on GbE
ᵒHowever limited to 2.9Gb/s in total
• But XenServer uses significantly more CPU cycles than Linux
ᵒLess available cycles for application
ᵒ10GbE networks: CPU saturation in dom0 prevents achieving line rate
• Need to reduce I/O virtualization overhead in XenServer networking


I/O Virtualization Overview – Hardware Solution

• VMDq (Virtual Machine Device Queue)
ᵒSeparate Rx & Tx queue pairs of NIC for Network Only
each VM, Software “switch”.
• Direct I/O (VT-d)
ᵒImproved I/O performance through direct VM exclusively
assignment of a I/O device to a HVM or PV owns device
workload
• SR-IOV (Single Root I/O Virtualization)
One Device, multiple
ᵒChanges to I/O device silicon to support
Virtual Functions
multiple PCI device ID’s, thus one I/O device
can support multiple direct assigned guests.
Requires VT-d.


Where Does SR-IOV Fit In?

Technique Efficiency Hardware Abstraction Applicability Scalability
Characteristic
Emulation Low Very high All device classes High

Para-virtualization Medium High – requires installing paravirtual Block, network High
drivers on the guest
Acceleration (VMDq) High Medium: Network only, Medium (for
-Transparent to apps hypervisor dependent accelerated interfaces)
-May require device-specific
accelerators
PCI Pass-through High Low: All devices Low
-Explicit device plug/unplug
-Device specific drivers

SR-IOV Addresses This


XenServer Solarflare SR-IOV Implementation
Typical SR-IOV Implementation XS & Solarflare SR-IOV Model
Guest Guest Guest
App VM App VM VM App

Plug-in
Netfront driver
VF driver VF driver
driver
VF

dom0 dom0
Netback
driver

vSwitch vSwitch

Physical
driver
Physical driver

Virtual NIC Virtual NIC NIC Virtual NIC NIC

Improved performance, but loss of services Improved performance AND full
and management (e.g. live migration) use of services and management


XenMotion – Live VM Migration

• Requires systems that have compatible CPUs
ᵒMust be the same manufacturer
ᵒCan be different speed
ᵒMust support maskable features; or be of simlar type (e.g. 3450 and 3430)

• Minimal Downtime
ᵒGenerally sub 200 mS; mostly due to network switches

• Requires shared storage
ᵒVM state moves between hosts; underlying disks remain in existing location


Pre-Copy Migration: Round 1
• Systems verify correct storage and network setup on destination server
• VM Resources Reserved on Destination Server

Source Virtual Machine Destination


• While source VM is still running XenServer copies over memory image to destination server
• XenServer keeps track of any memory changes during this process


• After first pass most of the memory image is now copied to the destination server
• Any memory changes during initial memory copy are tracked


• XenServer now does another pass at copying over changed memory


• Xen still tracks any changes during the second memory copy
• Second copy moves much less data
• Also less time for memory changes to occur


Pre-Copy Migration
• Xen will keep doing successive memory copies until minimal differences
between source and destination


XenMotion: Final
• Source VM is paused and last bit of memory and machine state copied over
• Master unlocks storage from source system and locks to destination system
• Destination VM is unpaused and attached to storage and network resources
• Source VM resources cleared


Upgrading VMs from Local to Shared Storage

Live
Virtual
Machine

XenServer Hypervisor
VDI(s)

Local
Storage

FC, iSCSI, NFS SAN XenServer Pool


Moving VMs within a Pool with local-only storage

Live
Virtual
Machine

XenServer Hypervisor XenServer Hypervisor
VDI(s)

Local Local
Storage Storage
XenServer Pool


Moving or rebalancing VMs between Pools (Local  SAN)

Live
Virtual
Machine

VDI(s)

Local
Storage FC, iSCSI, NFS SAN

XenServer Pool 1 XenServer Pool 2


Moving or rebalancing VMs between Pools (Local  Local)

Live
Virtual
Machine

VDI(s)

Local Local
Storage Storage
XenServer Pool 1 XenServer Pool 2


VHD Benefits

• Many SRs implement VDIs as VHD trees
• VHDs are a copy-on-write format for storing virtual disks
• VDIs are the leaves of VHD trees
• Interesting VDI operation: snapshot (implemented as VHD “cloning”)

RW RO

A
RO RW

B A
• A: Original VDI
• B: Snapshot VDI

no color = empty
VDI Mirroring Flow gradient = live
SOURCE DESTINATION

mirror
VM VM

root


Benefits of VDI Mirroring

• Optimization: start with most similar VDI
ᵒAnother VDI with the least number of different blocks
ᵒOnly transfer blocks that are different
• New VDI field: Content ID for each VDI
ᵒEasy way to confirm that different VDIs have identical content
ᵒPreserved across VDI copy, refreshed after VDI attached RW
• Worst case is a full copy (common in server virtualization)
• Best case occurs when you use VM “gold images” (i.e. XenDesktop)


Xen server 6.1 technical sales presentation

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