Planning and Implementation of a Provisioning High Availability (HA) Solution

Planning and Implementation of a Provisioning High Availability (HA) Solution

Keith T McLaughlin

Escalation Engineer

Training Agenda

Overview of two different High Availability configurations

Deeper look at High Availability Architecture

Design and Implementation

Troubleshooting Tips

Two different HA Configurations

Distributed HA

Centralized HA

Distributed HAProvisioning Servers

SQL Server

vDisks

SQL databaseTarget Devices

Centralized HAProvisioning Servers

Shared Storage

vDisks

SQL database Target Devices

SQL Server

High Availability Design

Agenda item number 1

Cache’s roll in High Availability

The roll of the bootstrap file in failover

Re-login Process

Load Balancing with High Availability

How does failover work?

Failover Process

1.1.1.1

1.1.1.2

1.1.1.3

1.1.1.4

Streaming from 1.1.1.4

X

Bootstrap1.1.1.2

1.1.1.1

Login Process

Request for vDisk3

PVS Target Device

StreamServer

1.1.1.3:vDisk3

Bootstrap’s roll in failover

• The Target Device uses the list of Provisioning Server provided in the bootstrap when initiating failover.

Role of the bootstrap

Shared Storage

vDisks

SQL database Target Devices

SQL Server

PVS3PVS1 PVS2

PVS6PVS5PVS4

BootstrapPVS1

PVS2

PVS3

PVS4

Load balancing with High Availability

• PVS currently only provides load balancing during the login process. A count of how many devices are booted to each server in the site is kept by the stream service.

• When a Target Device is shutdown or a new Target Device is booted up the server will update the count and send that information to all other servers in the site.

Load balancing with High Availability (cont)

• Load balancing will not occur dynamically after the login process.

PVS2PVS1

Load balancing with High Availability (cont)

PVS2PVS1

X

Where to store the cache file in a HA environment

Cache on local RAM

Cache on Server Disk

Cache on Local Disk

Cache on Local RAM

Shared Storage

vDisks

SQL database

Cache

PVS1 PVS2

X

Cache on Local Disk

Shared Storage

vDisks

SQL database

Cache

PVS1 PVS2

X

Cache on Server Disk

Shared Storage

vDisks

SQL database

Cache

PVS1 PVS2

X

Cache on Server Disk (incorrect configuration)

Shared Storage

vDisks

SQL database

Cache

PVS1 PVS2

X

Possible single point of failure

Shared Storage

vDisksSQL database

Cache

PVS1

PVS2

TFTPDHCP PXE

Switch

Possible single points of failure

TFTP

Network

Storage

Bootstrap Delivery

TFTP Redundancy

• DHCP Option 66 only allows for one TFTP server to be entered.

• Using TFTP Clustered Servers or PXE Service instead of DHCP options will solve this issue.

Network Redundancy

PVS Server Target Device

Switch

PVS Server Target Device

Storage Redundancy

Type of Storage Pros Cons

CIFS on Windows Server

• Easy to setup

• Free with OS

• Hard drives are cheap

• Performance due to SMB traffic

• Lack of scalability

• HA requires two plus servers

CIFS on NAS Device

Easy to setup Device typically less expensive than SAN

device Built in redundancy for disks (depends on

vendor/model) Various vendors/models

•Less expensive solutions equal single

point of failure

• Scalability can be an issue depending

on vendor/model purchased

Storage Redundancy (continued)

iSCSI to NAS Device

Moderate to setup Device typically less expensive than SAN

device Built in redundancy for disks (depends on

vendor/model) Various vendors/models offer resiliency

benefits

•Less expensive solutions equal single point of failure

•Scalability can be an issue depending on vendor/model purchased

•Requires cluster file system when sharing LUN across multiple servers

iSCSI to SAN Device

•Highly scalable•Built in resiliency

•Build in features like storage replication and high performance disk arrays

•Moderate to complex to setup•Typically more expensive than NAS devices•Requires cluster file system when sharing LUN across multiple servers

Storage Redundancy (continued)

Fiber to SAN Device

•Highly scalable•Built in resiliency

•Build in features like storage replication and high performance disk arrays

•Complex to setup•Typically more expensive than NAS devices•Requires cluster file system when sharing LUN across multiple servers

Bootstrap Delivery Redundancy

Solution Pros Cons

DHCP Clustering • Less traffic on the network

•Moderate to setup

• Multiple servers needed

• More expensive

Multiple PXE Servers

Easy to setup Less hardware needed.

•More broadcast traffic on the network

Troubleshooting Tips

Stream Logs

PVS Logging

• Log files and the stream_log.config files can be found in C:\Documents and Settings\All Users\Application Data\Citrix\Provisioning Server

• To increase the logging level edit the level value line in the stream_config to TRACE

• <level value="TRACE" />

PVS Logging

[0x00000188] TRACE CStreamDbImpl::DoDeviceGetByMac - In DoDeviceGetByMac for mac = E27AE23D9F48

[0x00000188] TRACE CSqlCommand::CSqlCommand - new CSqlCommand commandText: <uspGetDeviceByMac>

[0x00000188] TRACE CClientDeviceInstanceDbAccess::DoGetOne - In CClientDeviceInstanceDbAccess::DoGetOne

[0x00000188] DEBUG CClientDeviceInstanceDbAccess::DoGetOne - got device record, name = WinXp, mac = E27AE23D9F48

[0x00000188] DEBUG CStreamDbImpl::DoDiskLocatorGetByDeviceId - In DoDiskLocatorGetByDeviceId for id = 1

[0x00000188] TRACE CDiskLocatorInstanceDbAccess::DoGetByDeviceId - In CDiskLocatorInstanceDbAccess::DoGetByDeviceId

[0x00000188] TRACE CSqlCommand::CSqlCommand - new CSqlCommand commandText: <uspGetDiskLocatorByDeviceId>

[0x00000188] DEBUG

CDiskLocatorInstanceDbAccess::DoGetByDeviceId - harvested diskLocator info, diskLocatorId = 26fd6469-a761-4d0f-ae65-0288508fe93c, name = <vDISKNAME>, id = 3

[0x00000188] TRACE

CStreamDbImpl::DoDeviceBootstrapGetByGuid - In DoDeviceBootstrapGetByGuid for deviceId = 3b5be104-86c3-4862-8c3a-d4019fa8d5a1

[0x00000188] TRACE CStreamDbImpl::DoDeviceGetByMac - In DoDeviceGetByMac for mac = E27AE23D9F48

[0x00000188] DEBUG CClientDeviceInstanceDbAccess::DoGetOne - got device record, name = WinXp, mac = E27AE23D9F48

[0x00000188] DEBUG

CDiskLocatorInstanceDbAccess::DoGetByDeviceId - harvested diskLocator info, diskLocatorId = 26fd6469-a761-4d0f-ae65-0288508fe93c, name = <vDISKNAME>, id = 3

PVS Logging Continued

[0x00000188] TRACE

CServerInstanceDbAccess::DoChooseLeastBusyServerForDiskLocator - In DoChooseLeastBusyServerForDiskLocator

[0x00000188] DEBUG

CServerInstanceDbAccess::RoundRobinChooseLeastBusyServerForDiskLocator - found at least one leastBusy server, setting minDeviceCount = 0

[0x00000188] DEBUG

CServerInstanceDbAccess::RoundRobinChooseLeastBusyServerForDiskLocator - harvested leastBusyServer contact info, serverId = f5d9dab3-6f72-42b0-aae7-320f91c837eb, serverName = PVS2KEITH, deviceCount = 0

[0x00000188] DEBUG

CServerInstanceDbAccess::RoundRobinChooseLeastBusyServerForDiskLocator - choosing the first/only server, numLeastBusyServers = 1, target = 0

[0x00000188] DEBUG

CServerInstanceDbAccess::RoundRobinChooseLeastBusyServerForDiskLocator - found at least one leastBusy server, setting minDeviceCount = 0

[0x00000188] DEBUG

CServerInstanceDbAccess::RoundRobinChooseLeastBusyServerForDiskLocator - harvested leastBusyServer contact info, serverId = f5d9dab3-6f72-42b0-aae7-320f91c837eb, serverName = PVS2KEITH, deviceCount = 0

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