Using NFS as a filesystem type with HP Serviceguard A.11.20 on HP-UX 11i v3, September 2010

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Using NFS as a filesystem type with HP

Serviceguard A.11.20 on HP-UX 11i v3

Technical white paper

Table of contents

Introduction ......................................................................................................................................... 2

Audience ............................................................................................................................................ 2

Terms and Definitions ........................................................................................................................... 2

Serviceguard support for NFS on HP-UX 11i v3 ....................................................................................... 2

Overview ........................................................................................................................................ 2

Supported configurations .................................................................................................................. 3

Recommendations ............................................................................................................................ 3

Limitations ....................................................................................................................................... 3

Setting up the NFS server .................................................................................................................. 4

Configuring the NFS package and cluster parameters .......................................................................... 4

Creating a sample NFS package ....................................................................................................... 9

Sample cmviewcl line output ............................................................................................................... 11

For more information .......................................................................................................................... 12

Call to action .................................................................................................................................... 12

Summary of content (12 pages)

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Using NFS as a filesystem type with HP Serviceguard A.11.20 on HP-UX 11i v3 Technical white paper Table of contents Introduction ......................................................................................................................................... 2 Audience ............................................................................................................................................ 2 Terms and Definitions .....................................................................
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Introduction This white paper explains how to configure packages that need access to an NFS-imported filesystem as shared storage. This capability is available as of HP Serviceguard version A.11.20; in previous releases, Serviceguard has supported only direct-attached storage, using technologies such as SCSI, Fibre Channel, or SAS. Note: Although HP Serviceguard A.11.20 supports NFS-imported storage, direct attached storage is still recommended over NFS for performance reasons.
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Supported configurations • Supported only on HP-UX 11i v3. • Supported only for modular-style failover packages (see chapter 6 of the latest version of Managing Serviceguard for information about package types). • Supported only on Serviceguard A.11.20 or later Recommendations • If the storage is directly connected to all the nodes and shared, configure the storage as a local filesystem rather than using via NFS.
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• So that Serviceguard can ensure that all I/O from a node on which a package has failed is flushed before the package starts on an adoptive node, all the switches and routers between the NFS server and client must support a worst-case timeout, after which packets and frames are dropped. This timeout is known as the Maximum Bridge Transit Delay (MBTD). Switches and routers that do not support MBTD must not be used in a Serviceguard configuration.
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To prevent this, you must determine a maximum delay between when a write is issued from any Serviceguard node and when it can arrive at the NFS server. Use the discussion that follows for guidance. The NFS write may go through network switches before it reaches the NFS server. In each switch, the packet will be dropped after some specific time has elapsed. The IEEE Bridge specification, 802.1D, refers to this value as ‘Maximum Bridge Transit Delay’ (MBTD).
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Figure 1: The NFS client and the NFS server with one network switch configured between them If there is more than one switch between the NFS server and the Serviceguard nodes, set CONFIGURED_IO_TIMEOUT_EXTENSION to the sum of the MBTD values for each of the switches in the path (remember to use microseconds).
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Figure 2: The NFS client and the NFS server with two network switches configured between them In the example in Figure 3, there are multiple routes or paths between the NFS server and the NFS client, and the packet can travel by any path. Configure CONFIGURED_IO_TIMEOUT_EXTENSION to sum of the MBTD values in the longest route.
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Figure 3: The NFS client and the NFS server use more than one route to communicate When the NFS client writes packets from the NFS client to the NFS server, the data might travel through switch 1 and 2, or instead go through switch 3 and reach the NFS server. For path 1 (via switch 1 and switch 2) the sum of the MBTD values is 2 seconds. For path 2 (via switch 3) the MBTD value is 1 second. In this case, set CONFIGURED_IO_TIMEOUT_EXTENSION is to 2000000.
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Creating a sample NFS package You can use Serviceguard Manager to create Serviceguard packages. If you decide instead to use Serviceguard commands to create packages, follow these steps to create a package that uses NFSimported storage. – Before you start: Verify that the cluster configuration adheres to the recommendations and guidelines in this white paper. – Step 1: Set the CONFIGURED_IO_TIMEOUT_EXTENSION parameter as described in section 4.3.
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– Step 5: Check the package configuration file. truck:/>cmcheckconf -v -P pkg.ascii Begin package verification... Checking existing configuration ... Done Attempting to add package NFSPkg. Validating package NFSPkg via /etc/cmcluster/scripts/mscripts/master_control_script.sh ... Waiting for up to 1200 seconds for the validation. Validation for package NFSPkg succeeded via /etc/cmcluster/scripts/mscripts/master_control_script.sh. Maximum configured packages parameter is 300. Configuring 1 package(s).
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– Step 7: Start the cluster if it is not already running. Run the package. truck:/>cmrunpkg NFSPkg Running package NFSPkg on node blocks Successfully started package NFSPkg on node blocks cmrunpkg: All specified packages are running – Step 8: Verify that the package is up and running. truck:/>cmviewcl -p NFSPkg PACKAGE NFSPkg STATUS up STATE AUTO_RUN NODE running enabled blocks Sample cmviewcl line output The cmviewcl line output is enhanced to display the NFS server.
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For more information To learn more, please visit: • HP Serviceguard Solutions for HP-UX 11i: www.hp.com/go/serviceguardsolutions For technical documentation: • HP Serviceguard Solutions for HP-UX 11i: www.hp.com/go/hpux-serviceguard-docs • Managing Serviceguard Manual: www.hp.com/go/hpux-serviceguard-docs  HP Serviceguard  User Guide • HP Serviceguard NFS Toolkit: www.hp.com/go/hpux-serviceguard-docs  HP Serviceguard NFS Toolkit • HP Serviceguard NFS Toolkit Administrator's Guide: http://bizsupport1.