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The Availability Equation – High Availability Solutions

December 9, 2018 by Jason Aw Leave a Comment

The Availability Equation

Are you familiar with the Availability Equation? In a nutshell, this equation shows how the total time needed to restore an application to usability is equal to the time required to detect that an application is experiencing a problem plus the time required to perform a recovery action:

T_RESTORE = T_DETECT + T_RECOVER

Key Concepts Of High Availability Solutions

The equation introduces the key concepts of high availability (HA): clustering, problem detection, and subsequent recovery. HA solutions monitor the health of business application components; when problems are detected, these solutions act to restore them to service. The objective of deploying high availability solutions is to minimize downtime.

Reducing detection and recovery times are two important tasks of any HA solution that you choose to deploy. Today’s applications are combinations of technologies: servers, storage, network infrastructure, and so on. When reviewing your HA options, be certain that you understand the technologies that each solution uses to detect and recover from all outage types. Each technology has a direct impact on service restoration times.

Local Detection And Recovery

High availability solutions are straightforward. One technology that is crucial to providing the fastest possible restoration time is known as local detection and recovery (aka service-level problem detection and recovery). In a basic clustering solution, servers are connected. They are configured that one or more servers can take over the operations of another in the event of a server failure. The server nodes in the cluster continuously send small data packets, often called heartbeat signals, to each other to indicate that they are “alive”.

In simple clustered environments, when one server stops generating heartbeats, other cluster members assume that this server is down. It will then begin the process of taking over responsibility for that server’s domain of operation. This approach is adequate for detecting failure at the server level. But unless problems cause the interruption or cessation of heartbeat signals, server-level detection is inadequate. More than that, it can actually magnify the extent and impact of an outage.

For example, if Apache processes hang, the server may still send heartbeats. Even though the Web server subsystem has ceased to perform its primary function. Rather than restart the Apache subsystem on the same or a different server, a basic server-level clustering solution would restart the entire software stack of the failed server on a backup server, thereby causing interruption to users and extending recovery time.

How It Works

Using local detection and recovery, advanced clustering solutions deploy health-monitoring agents within individual cluster servers, to monitor individual system components such as a file system, a database, user-level application, IP address, and so on. These agents use heuristics that are specific to the monitored component. Therefore, the agents can predict and detect operational issues and then take the most appropriate recovery action. Often, the most efficient recovery method is to stop and restart the problem subsystem on the same server.

The time to restore an application to user availability can be greatly reduced by enabling recovery within the same physical server. Also, by detecting failures at a more granular level than simply by observing server-level heartbeats. Solutions such as the SteelEye Protection Suite for Linux from SIOS provides this level of detection and recovery for your environment. Make certain that whichever HA solution you deploy can also support local detection and recovery.

Would you like to enjoy high availability solutions for your projects? Check in with us. Need more references, here are our success stories.
Reproduced with permission from Linuxclustering

12 Checklist Items for Selecting a High-Availability Solution

December 6, 2018 by Jason Aw Leave a Comment

12 Checklist Items For Selecting A High-Availability Solution

When selecting a high-availability solution, you should consider several criteria. These range from the total cost of the solution, to the ease with which you can configure and manage the cluster, to the specific restrictions placed on hardware and software. This post touches briefly on 12 of the most important checklist items.

1. Support For Standard OS And Application Versions

Solutions that require enterprise or advanced versions of the OS, database, or application software can greatly reduce the cost benefits of moving to a commodity server environment. Deploy the proper HA middleware. This way, you can make standard versions of applications and OSs highly available. And at the same time, meet the uptime requirements of your business environment.

2. Support For A Variety Of Data Storage Configurations

When you deploy an HA cluster, the data that the protected applications require must be available to all systems that might need to bring the applications into service. You can share this data via data replication, by using shared SCSI or Fibre Channel storage, or by using a NAS device. Whichever method you decide to deploy, the HA product that you use must be able to support all data configurations so that you can change as your business needs dictate.

3. Ability To Use Heterogeneous Solution Components

Some HA clustering solutions require that every system within the cluster has identical configurations. This requirement is common among hardware-specific solutions in which clustering technology is meant to differentiate servers or storage and among OS vendors that want to limit the configurations they are required to support. This restriction limits your ability to deploy scaled-down servers as temporary backup nodes and to reuse existing hardware in your cluster deployment. Deploying identically configured servers might be the correct choice for your needs, but the decision shouldn’t be dictated by your HA solution provider.

4. Support For More Than Two Nodes Within A Cluster

The number of nodes that can be supported in a cluster is an important measure of scalability. Entry-level HA solutions typically limit you to one two-node cluster, usually in active/passive mode. Although this configuration provides increased availability (via the addition of a standby server), it can still leave you exposed to application downtime. In a two-node cluster configuration, if one server is down for any reason, then the remaining server becomes a single point of failure. By clustering three or more nodes, you gain the ability to provide higher levels of protection. At the same time, you can also build highly scalable configurations.

5. Support For Active/Active And Active/Standby Configurations

Selecting a High-Availability Solution to suit your project is key. In an active/standby configuration, one server is idle, waiting to take over the workload of its cluster member. This setup has the obvious disadvantage of underutilizing your compute resource investment. To get the most benefit from your IT expenditure, ensure that cluster nodes can run in an active/active configuration.

6. Detection Of Problems At Node And Individual Service Levels

All HA software products can detect problems with cluster server functionality. This task is done by sending heartbeat signals between servers within the cluster and initiating a recovery if a cluster member stops delivering the signals. But advanced HA solutions can also detect another class of problems. One that occurs when individual processes or services encounter problems that render them unavailable but that do not cause servers to stop sending or responding to heartbeat signals. Given that the primary function of HA software is to ensure that applications are available to end users, detecting and recovering from these service level interruptions is a crucial feature. Ensure that your HA solution can detect both node- and service-level problems.

7. Support For In-Node And Cross-Node Recovery

The ability to perform recovery actions both across cluster nodes and within a node is also important. In cross-node recovery, one node takes over the complete domain of responsibility for another. When systems-level heartbeats are missed, the server which should have sent the heartbeats is assumed to be out of operation, and other cluster members begin recovery operations. With in-node or local recovery, failed system services first attempt to be restored within the server on which they are running. This task is typically done by stopping and restarting the service and any dependent system resources. This recovery method is much faster and minimizes downtime.

8. Transparency To Client Connections Of Server-Side Recovery

Server-side recovery of an application or even of an entire node should be transparent to client-side users. Through the use of virtualized IP addresses or server names, the mapping of virtual compute resources onto physical cluster entities during recovery, and automatic updating of network routing tables, no changes to client systems are necessary for the systems to access recovered applications and data. Solutions that require manual client-side configuration changes to access recovered applications greatly increase recovery time. They introduce the risk of additional errors due to required human interaction. Recovery should be automated on both the servers and clients.

9. Protection For Planned And Unplanned Downtime

In addition to providing protection against unplanned service outages, the HA solution that you deploy should be usable as an administration tool to lessen downtime caused by maintenance activities. By providing a facility to allow on-demand movement of applications between cluster members, you can migrate applications and users onto a second server while performing maintenance on the first. This can eliminate the need for maintenance windows in which IT resources are unavailable to end users. Ensure that your HA solution provides a simple and secure method for performing manual (on-demand) movement of applications and needed resources among cluster nodes.

10. Off-The-Shelf Protection For Common Business Functions

Every HA solution that you evaluate should include tested and supported agents or modules that are designed to monitor the health of specific system resources: file systems, IP addresses, databases, applications, and so on. These modules are often called recovery modules. By deploying vendor-supplied modules, you benefit from both the run-time that the vendor and other customers have already done. You also have the assurance of ongoing support and maintenance of these solution components.

11. Ability To Easily Incorporate Protection For Custom Business Applications

There will likely be applications, perhaps custom to your corporation, that you want to protect but for which there are no vendor-supplied recovery modules. It is important, therefore, that you have a method for easily incorporating your business application into your HA solution’s protection schema. You should be able to do this without modifying your application, and especially without having to embed any vendor-specific APIs. A software developer’s kit that provides examples and a step-by-step process for protecting your application should be available. Also, along with vendor-supplied support services to assist as needed.

12. Ease Of Cluster Deployment And Management

A common myth surrounding HA clusters is that they are costly and complex to deploy and administer. This is not necessarily true. Cluster administration interfaces should be wizard-driven to assist with initial cluster configuration. It should include auto-discovery of new elements as they are added to the cluster. Similarly, it should allow for at-a-glance status monitoring of the entire cluster. Finally, any cluster metadata must be stored in an HA fashion. Not on a single quorum disk within the cluster, where corruption or an outage could cause the entire cluster to fall apart.

By looking for the capabilities on this checklist, you can make the best decision for your particular HA needs.

Selecting a High-Availability Solution isn’t rocket science. Here are our success stories

Reproduced with permission from Linuxclustering

Do You Know How Much Bandwidth To Support Real-Time Replication?

December 5, 2018 by Jason Aw Leave a Comment

How Much Bandwidth To Support Real-Time Replication?

When you want to replicate data across multi-site or wide area network (WAN) configurations, you first need to answer one important question: Is there sufficient bandwidth to successfully replicate the partition and keep the mirror in the mirroring state as the source partition is updated throughout the day? Keeping the mirror in the mirroring state is crucial. A partition switchover is allowed only when the mirror is in the mirroring state.

Therefore, an important early step to figure out how much Bandwidth To Support Real-Time Replication is determining your network bandwidth requirements. How can you measure the rate of change—the value that indicates the amount of network bandwidth needed to replicate your data?

Establish Basic Rate of Change

First, use these commands to determine the basic daily rate of change for the files or partitions that you want to mirror; for example, to measure the amount of data written in a day for /dev/sda3, run this command at the beginning of the day:

MB_START=`awk ‘/sda3 / { print $10 / 2 / 1024 }’ /proc/diskstats`

Wait for 24 hours, then run this command:

MB_END=`awk ‘/sda3 / { print $10 / 2 / 1024 }’ /proc/diskstats`

The daily rate of change, in megabytes, is then MB_END – MB_START.

The amounts of data that you can push through various network connections are as follows:

For T1 (1.5Mbps): 14,000 MB/day (14 GB)
For T3 (45Mbps): 410,000 MB/day (410 GB)
For Gigabit (1Gbps): 5,000,000 MB/day (5 TB)

Establish Detailed Rate of Change

What’s next to calculate Bandwidth To Support Real-Time Replication? You’ll need to measure detailed rate of change. The best way to collect this data is to log disk write activity for some period (e.g., one day) to determine the peak disk write periods. To do so, create a cron job that will log the timestamp of the system followed by a dump of /proc/diskstats. For example, to collect disk stats every 2 minutes, add this link to /etc/crontab:

*/2 * * * * root ( date ; cat /proc/diskstats ) >> /path_to/filename.txt

Wait for the determined period (e.g., one day, one week), then disable the cron job and save the resulting /proc/diskstats output file in a safe location.

Analyze and Graph Detailed Rate of Change Data

Next you should analyze the detailed rate of change data. You can use the roc-calc-diskstats utility for this task. This utility takes the /proc/diskstats output file and calculates the rate of change of the disks in the dataset. To run the utility, use this command:

# ./roc-calc-diskstats <interval> <start_time> <diskstats-data-file> [dev-list]

For example, the following dumps a summary (with per-disk peak I/O information) to the output file results.txt:

# ./roc-calc-diskstats 2m “Jul 22 16:04:01” /root/diskstats.txt sdb1,sdb2,sdc1 > results.txt

Here are sample results from the results.txt file:

Sample start time: Tue Jul 12 23:44:01 2011

Sample end time: Wed Jul 13 23:58:01 2011

Sample interval: 120s #Samples: 727 Sample length: 87240s

(Raw times from file: Tue Jul 12 23:44:01 EST 2011, Wed Jul 13 23:58:01 EST 2011)

Rate of change for devices dm-31, dm-32, dm-33, dm-4, dm-5, total

dm-31 peak:0.0 B/s (0.0 b/s) (@ Tue Jul 12 23:44:01 2011) average:0.0 B/s (0.0 b/s)

dm-32 peak:398.7 KB/s (3.1 Mb/s) (@ Wed Jul 13 19:28:01 2011) average:19.5 KB/s (156.2 Kb/s)

dm-33 peak:814.9 KB/s (6.4 Mb/s) (@ Wed Jul 13 23:58:01 2011) average:11.6 KB/s (92.9 Kb/s)

dm-4 peak:185.6 KB/s (1.4 Mb/s) (@ Wed Jul 13 15:18:01 2011) average:25.7 KB/s (205.3 Kb/s)

dm-5 peak:2.7 MB/s (21.8 Mb/s) (@ Wed Jul 13 10:18:01 2011) average:293.0 KB/s (2.3 Mb/s)

total peak:2.8 MB/s (22.5 Mb/s) (@ Wed Jul 13 10:18:01 2011) average:349.8 KB/s (2.7 Mb/s)

To help you understand your specific bandwidth needs over time, you can graph the detailed rate of change data. The following dumps graph data to results.csv (as well as dumping the summary to results.txt):

# export OUTPUT_CSV=1

# ./roc-calc-diskstats 2m “Jul 22 16:04:01” /root/diskstats.txt sdb1,sdb2,sdc1 2> results.csv > results.txt

SIOS has created a template spreadsheet, diskstats-template.xlsx, which contains sample data that you can overwrite with your data from roc-calc-diskstats. The following series of images show the process of using the spreadsheet.

Open results.csv, and select all rows, including the total column.

Open diskstats-template.xlsx, select the diskstats.csv worksheet.

In cell 1-A, right-click and select Insert Copied Cells.
Adjust the bandwidth value in the cell towards the bottom left of the worksheet (as marked in the following figure) to reflect the amount of bandwidth (in megabits per second) that you have allocated for replication. The cells to the right are automatically converted to bytes per second to match the collected raw data.

Take note of the following row and column numbers:

- Total (row 6 in the following figure)
- Bandwidth (row 9 in the following figure)
- Last datapoint (column R in the following figure)

Select the bandwidth vs ROC worksheet.

Right-click the graph and choose Select Data.
In the Select Data Source dialog box, choose bandwidth in the Legend Entries (Series) list, and then click Edit.

In the Edit Series dialog box, use the following syntax in the Series values field: =diskstats.csv!$B$<row>:$<final_column>$<row> The following figure shows the series values for the spread B9 to R9.

Click OK to close the Edit Series box.
In the Select Data Source box, choose ROC in the Legend Entries (Series) list, and then click Edit.

In the Edit Series dialog box, use the following syntax in the Series values field: =diskstats.csv!$B$<row>:$<final_column>$<row> The following figure shows the series values for the spread B6 to R6.

Click OK to close the Edit Series box, then click OK to close the Select Data Source box.

The Bandwidth vs ROC graph updates. Analyze your results to determine whether you have sufficient bandwidth to support data replication.

Next Steps

If your Rate of Change exceeds your available bandwidth, you will need to consider some of the following points to ensure your replication solution performs optimally:

Enable compression in your replication solution or in the network hardware. (DataKeeper for Linux, which is part of the SteelEye Protection Suite for Linux, supports this type of compression.)
Create a local, non-replicated storage repository for temporary data and swap files that don’t need to be replicated.
Reduce the amount of data being replicated.
Increase your network capacity.

For quick how-tos like figuring Bandwidth To Support Real-Time Replication, read our blog

Reproduced with permission from Linuxclustering

SAP High Availability Solutions For Linux

December 3, 2018 by Jason Aw Leave a Comment

SAP High Availability Solutions For Linux

Are you looking for a powerful yet easy to implement High Availability / Disaster Recovery solution for your SAP environment? If so, you will want to take a look at the SteelEye Protection Suite (SPS) for Linux, from SIOS Technologies. SPS provides integrated High Availability and Data Replication functionality that works with any server or storage configuration. Support for SAP is provided out-of-the-box without the need for any scripting or customizations.

SPS for Linux was recently officially certified by SAP against their “SAP NetWeaver High Availability Cluster 730 Certification” (NW-HA-CLU 730)

A list of certified HA solutions for SAP can be found here: http://scn.sap.com/docs/DOC-31701

For more information on SAP High Availability Solutions For Linux, do drop us a note
Reproduced with permission from Linuxclustering

How to Create a 2-Node MySQL Cluster Without Shared Storage – Part 2

November 30, 2018 by Jason Aw Leave a Comment

Step-by-Step: How To Create A 2-Node MySQL Cluster Without Shared Storage, Part 2

The previous post introduced the advantages of running a MySQL cluster, using a shared-nothing storage configuration. We also began walking through the process of setting up the cluster, using data replication and SteelEye Protection Suite (SPS) for Linux. In this post, we complete the process to Create a 2-Node MySQL Cluster Without Shared Storage. Let’s get started.

Creating Comm Paths

Now it’s time to access the SteelEye LifeKeeper GUI. LifeKeeper is an integrated component of SPS for Linux. The LifeKeeper GUI is a Java-based application that can be run as a native Linux app or as an applet within a Java-enabled Web browser. (The GUI is based on Java RMI with callbacks, so hostnames must be resolvable or you might receive a Java 115 or 116 error.)

To start the GUI application, enter this command on either of the cluster nodes: /opt/LifeKeeper/bin/lkGUIapp & Or, to open the GUI applet from a Web browser, go to http://<hostname>:81.

The first step is to make sure that you have at least two TCP communication (Comm) paths between each primary server and each target server, for heartbeat redundancy. This way, the failure of one communication line won’t cause a split-brain situation. Verify the paths on the primary server. The following screenshots walk you through the process of logging into the GUI, connecting to both cluster nodes, and creating the Comm paths.

Step 1: Connect to primary server

Step 2: Connect to secondary server

Step 3: Create the Comm path

Step 4: Choose the local and remote servers

Step 5: Choose device type

Next, you are presented with a series of dialogue boxes. For each box, provide the required information and click Next to advance. (For each field in a dialogue box, you can click Help for additional information.)

Step 6: Choose IP address for local server to use for Comm path

Step 7: Choose IP address for remote server to use for Comm path

Step 8: Enter Comm path priority on local server

After entering data in all the required fields, click Create. You’ll see a message that indicates that the network Comm path was successfully created.

Step 9: Finalize Comm path creation

Click Next. If you chose multiple local IP addresses or remote servers and set the device type to TCP, then the procedure returns you to the setup wizard to create the next Comm path. When you’re finished, click Done in the final dialogue box. Repeat this process until you have defined all the Comm paths you plan to use.

Verify that the communications paths are configured properly by viewing the Server Properties dialogue box. From the GUI, select Edit > Server > Properties, and then choose the CommPaths tab. The displayed state should be ALIVE. You can also check the server icon in the right-hand primary pane of the GUI. If only one Comm path has been created, the server icon is overlayed with a yellow warning icon. A green heartbeat checkmark indicates that at least two Comm paths are configured and ALIVE.

Step 10: Review Comm path state

Creating And Extending An IP Resource

In the LifeKeeper GUI, create an IP resource and extend it to the secondary server by completing the following steps. This virtual IP can move between cluster nodes along with the application that depends on it. By using a virtual IP as part of your cluster configuration, you provide seamless redirection of clients upon switchover or failover of resources between cluster nodes because they continue to access the database via the same FQDN/IP.

Step 11: Create resource hierarchy

Step 12: Choose IP ARK

Enter the appropriate information for your configuration, using the following recommended values. (Click the Help button for further information.) Click Next to continue after entering the required information.

Field	Tips
Resource Type	Choose IP Address as the resource type and click Next.
Switchback Type	Choose Intelligent and click Next.
Server	Choose the server on which the IP resource will be created. Choose your primary server and click Next.
IP Resource	Enter the virtual IP information and click Next.(This is an IP address that is not in use anywhere on your network. All clients will use this address to connect to the protected resources.)
Netmask	Enter the IP subnet mask that your TCP/IP resource will use on the target server. Any standard netmask for the class of the specific TCP/IP resource address is valid. The subnet mask, combined with the IP address, determines the subnet that the TCP/IP resource will use and should be consistent with the network configuration.This sample configuration 255.255.255.0 is used for a subnet mask on both networks.
Network Connection	Enters the physical Ethernet card with which the IP address interfaces. Chose the network connection that will allow your virtual IP address to be routable. Choose the correct NIC and click Next.
IP Resource Tag	Accept the default value and click Next. This value affects only how the IP is displayed in the GUI. The IP resource will be created on the primary server.

LifeKeeper creates and validates your resource. After receiving the message that the resource has been created successfully, click Next.

Step 13: Review notice of successful resource creation

Now you can complete the process of extending the IP resource to the secondary server.

Step 14: Extend IP resource to secondary server

The process of extending the IP resource starts automatically after you finish creating an IP address resource and click Next. You can also start this process from an existing IP address resource, by right-clicking the active resource and selecting Extend Resource Hierarchy. Use the information in the following table to complete the procedure.

Field	Recommended Entries or Notes
Switchback Type	Leave as intelligent and click Next.
Template Priority	Leave as default (1).
Target Priority	Leave as default (10).
Network Interface	This is the physical Ethernet card with which the IP address interfaces. Choose the network connection that will allow your virtual IP address to be routable. The correct physical NIC should be selected by default. Verify and then click Next.
IP Resource Tag	Leave as default.
Target Restore Mode	Choose Enable and click Next.
Target Local Recovery	Choose Yes to enable local recovery for the SQL resource on the target server.
Backup Priority	Accept the default value.

After receiving the message that the hierarchy extension operation is complete, click Finish and then click Done.

Your IP resource (example: 192.168.197.151) is now fully protected and can float between cluster nodes, as needed. In the LifeKeeper GUI, you can see that the IP resource is listed as Active on the primary cluster node and Standby on the secondary cluster node.

Step 15: Review IP resource state on primary and secondary nodes

Creating A Mirror And Beginning Data Replication

Halfway to Create a 2-Node MySQL Cluster Without Shared Storage! You’re ready to set up and configure the data replication resource, which you’ll use to synchronize MySQL data between cluster nodes. For this example, the data to replicate is in the /var/lib/mysql partition on the primary cluster node. The source volume must be mounted on the primary server, the target volume must not be mounted on the secondary server, and the target volume size must be equal to or larger than the source volume size.

The following screenshots illustrate the next series of steps.

Step 16: Create resource hierarchy

Step 17: Choose Data Replication ARK

Use these values in the Data Replication wizard.

Field	Recommended Entries or Notes
Switchback Type	Choose Intelligent.
Server	Choose LinuxPrimary (the primary cluster node or mirror source).
Hierarchy Type	Choose Replicate Existing Filesystem.
Existing Mount Point	Choose the mounted partition to replicate; in this example, /var/lib/mysql.
Data Replication Resource Tag	Leave as default.
File System Resource Tag	Leave as default.
Bitmap File	Leave as default.
Enable Asynchronous Replication	Leave as default (Yes).

Click Next to begin the creation of the data replication resource hierarchy. The GUI will display the following message.

Step 18: Begin creation of Data Replication resource

Click Next to begin the process of extending the data replication resource. Accept all default settings. When asked for a target disk, choose the free partition on your target server that you created earlier in this process. Make sure to choose a partition that is as large as or larger than the source volume and that is not mounted on the target system.

Step 19: Begin extension of Data Replication resource

Eventually, you are prompted to choose the network over which you want the replication to take place. In general, separating your user and application traffic from your replication traffic is best practice. This sample configuration has two separate network interfaces, our “public NIC” on the 192.168.197.X subnet and a “private/backend NIC” on the 192.168.198.X subnet. We will configure replication to go over the back-end network 192.168.198.X, so that user and application traffic is not competing with replication.

Step 20: Choose network for replication traffic

Click Next to continue through the wizard. Upon completion, your resource hierarchy will look like this:

Step 21: Review Data Replication resource hierarchy

Creating The MySQL Resource Hierarchy

You need to create a MySQL resource to protect the MySQL database and make it highly available between cluster nodes. At this point, MySQL must be running on the primary server but not running on the secondary server.

From the GUI toolbar, click Create Resource Hierarchy. Select MySQL Database and click Next. Proceed through the Resource Creation wizard, providing the following values.

Field	Recommended Entries or Notes
Switchback Type	Choose Intelligent.
Server	Choose LinuxPrimary (primary cluster node).
Location of my.cnf	Enter /var/lib/mysql. (Earlier in the MySQL configuration process, you created a my.cnf file in this directory.)
Location of MySQL executables	Leave as default (/usr/bin) because you’re using a standard MySQL install/configuration in this example.
Database tag	Leave as default.

Click Create to define the MySQL resource hierarchy on the primary server. Click Next to extend the file system resource to the secondary server. In the Extend wizard, choose Accept Defaults. Click Finish to exit the Extend wizard. Your resource hierarchy should look like this:

Step 22: Review MySQL resource hierarchy

Creating The MySQL IP Address Dependency

Next, you’ll configure MySQL to depend on a virtual IP (192.168.197.151) so that the IP address follows the MySQL database as it moves.

From the GUI toolbar, right-click the mysql resource. Choose Create Dependency from the context menu. In the Child Resource Tag drop-down menu, choose ip-192.168.197.151. Click Next, click Create Dependency, and then click Done. Your resource hierarchy should now look like this:

Step 23: Review MySQL IP resource hierarchy

At this point in the evaluation, you’ve fully protected MySQL and its dependent resources (IP addresses and replicated storage). Test your environment, and you’re ready to go.

You can find much more information and detailed steps for every stage of the evaluation process in the SIOS SteelEye Protection Suite for Linux MySQL with Data Replication Evaluation Guide. To download an evaluation copy of SPS for Linux, visit the SIOS website or contact SIOS at info@us.sios.com.

Interested to learn to Create a 2-Node MySQL Cluster Without Shared Storage, here’s our past success stories with satisfied clients.
Reproduced with permission from Linuxclustering