Additional I/O Fencing Information

This section provides additional information about I/O fencing, including an extended description of the vxfentsthdw command, vxfenadm command, and a description of I/O fencing behavior to protect data in certain scenarios.

vxfentsthdw Options

The table below describes three methods the utility provides to test storage devices.

vxfentsthdw option

Description

When to Use

-m

Utility runs manually, in interactive mode, prompting for systems and devices, and reporting success or failure.

May be used with -r and -t options.

-m is the default option.

For testing a few disks or for sampling disks in larger arrays.

-f filename

Utility tests system/device combinations listed in a text file.

May be used with -r and -t options.

For testing several disks.

-g disk_group

Utility tests all disk devices in a specified disk group.

May be used with -r and -t options.

For testing many disks and arrays of disks. Disk groups may be temporarily created for testing purposes and destroyed (ungrouped) after testing.

Using the -r Option for Non-destructive Testing

To test disk devices containing data you want to preserve, you can use the -r option with the -m, -f, or -g options, which are described in the following sections. For example, to use the -m option and the -r option, you can run the utility by entering:

# /opt/VRTSvcs/vxfen/bin/vxfentsthdw -rm

When invoked with the -r option, the utility does not use tests that write to the disks. Therefore, it does not test the disks for all of the usual conditions of use.

Using the -m Option

The -m option is the default option for vxfentsthdw and is described in detail in Running vxfentsthdw.

Using the -f Option: Example

Use the -f option to test disks that are listed in a text file. For example, you can create a file to test two disks shared by systems north and south that might resemble:

north /dev/rdsk/c1t12d0 south /dev/rdsk/c2t12d0
north /dev/rdsk/c1t13d0 south /dev/rdsk/c2t13d0

where the first disk is listed in the first line and is seen by north as /dev/rdsk/c1t12d0 and by south as /dev/rdsk/c2t12d0. The other disk, in the second line, is seen as /dev/rdsk/c1t13d0 from north and /dev/rdsk/c2t13d0 from south. Typically, the list of disks could be extensive.

Suppose you created the file named disks_blue. To test the disks, you would enter:

# /opt/VRTSvcs/vxfen/bin/vxfentsthdw -f disks_blue

The utility reports the test results one disk at a time, just as for the -m option.

You can redirect the test results to a text file. Precede the command with "yes" to acknowledge that the testing destroys any data on the disks to be tested.

Caution Be advised that by redirecting the command's output to a file, a warning that the testing destroys data on the disks cannot be seen until the testing is done.

For example:

# yes | /opt/VRTSvcs/vxfen/bin/vxfentsthdw -f disks_blue > blue_test.txt

Using the -g Option: Example

Use the -g option to test all disks within a disk group. For example, you create a temporary disk group consisting of all disks in a disk array and test the group.

Note Do not import the test disk group as shared; that is, do not use the -s option.

The utility reports the test results one disk at a time. You can redirect the test results to a text file for review.

# /opt/VRTSvcs/vxfen/bin/vxfentsthdw -g red_disks_dg > redtest.txt

After testing, destroy the disk group and put the disks into disk groups as you need.

Testing a Disk with Existing Keys

If the utility detects that a coordinator disk has existing keys, you see a message that resembles:

There are VERITAS I/O Fencing keys on the disk. Please make sure
that I/O Fencing is shut down on all nodes of the cluster before
continuing.
******** WARNING!!!!!!!! ********
THIS SCRIPT CAN ONLY BE USED IF THERE ARE NO OTHER ACTIVE NODES IN
THE CLUSTER! VERIFY ALL OTHER NODES ARE POWERED OFF OR INCAPABLE
OF ACCESSING SHARED STORAGE.

If this is not the case, data corruption will result.
Do you still want to continue : [y/n] (default: n) y

The utility prompts you with a warning before proceeding. You may continue as long as I/O fencing is not yet configured.


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Manual: Cluster Server 4.1 Installation Guide
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