Study on Management Agent Failover and Refresh Mechanism Esquivel C. Malillos CS526

Introduction Currently implemented by Hewlett Packard’s HSV Element Manager software application. Currently implemented by Hewlett Packard’s HSV Element Manager software application. Manage and monitor a proprietary controller array called Enterprise Virtual Array (EVA) Manage and monitor a proprietary controller array called Enterprise Virtual Array (EVA) Written as Java applet. Written as Java applet. Agent Failover Agent Failover Refresh Mechanism Refresh Mechanism

Storage Area Network High speed special-purpose network. High speed special-purpose network. Use fiber channel technology. Use fiber channel technology. Supports disk mirroring, backup and restore, data migration from one storage device to another. Supports disk mirroring, backup and restore, data migration from one storage device to another. Replication Replication Sharing of data among different servers in the network Sharing of data among different servers in the network From

Web-Based Enterprise Management Unifying mechanism for describing and sharing management information. Unifying mechanism for describing and sharing management information. Common UI framework. Common UI framework. Problem addressed: Multiple platforms have no easy way to obtain management data from different operating system - proprietary API or console for each application. Problem addressed: Multiple platforms have no easy way to obtain management data from different operating system - proprietary API or console for each application.

Management Agent Application running in a management server that manages and monitors storage array. Application running in a management server that manages and monitors storage array. Serves as an intermediary server between the storage array and web browser client (WBEM). Serves as an intermediary server between the storage array and web browser client (WBEM). Storage Array could be managed by multiple agents either in active-active or active-passive mode. Storage Array could be managed by multiple agents either in active-active or active-passive mode. Storage Array could be accessed through multiple web browser clients. Storage Array could be accessed through multiple web browser clients. Multiple agents maintain a same view of the SAN and EVA by accessing a common Management Logical Disk (MLD) that serves as the controller’s database through firmware’s API. Multiple agents maintain a same view of the SAN and EVA by accessing a common Management Logical Disk (MLD) that serves as the controller’s database through firmware’s API.

Management Agent Web Screen Shot

Failover and Refresh Applet Java applet that runs in the background of the web browser. Java applet that runs in the background of the web browser. Send keep-alive message to the agent in a regular interval. Send keep-alive message to the agent in a regular interval. Two information is available from the server’s reply to the poll: agent list and status information. Two information is available from the server’s reply to the poll: agent list and status information. Automatically or manually redirects the browser to another agent. Automatically or manually redirects the browser to another agent. Use status information for browser refresh mechanism. Use status information for browser refresh mechanism.

Applet Parameters Run – enables/disables loading and initialization of the applet. Run – enables/disables loading and initialization of the applet. Auto – enables/disables agent failover without user interaction. Auto – enables/disables agent failover without user interaction. States – list of status fields the applet is to monitor for changes. States – list of status fields the applet is to monitor for changes. Poll - enables/disables polling of the server. Poll - enables/disables polling of the server. Interval – time interval between applet polls. Interval – time interval between applet polls. Retry – number of attempts to connect with the server before declaring an agent failure. Retry – number of attempts to connect with the server before declaring an agent failure.

Agent Failover Mechanism When it happens? If the management agent did not respond to a keep-alive message sent by the applet after a fixed count of retries. If the management agent did not respond to a keep-alive message sent by the applet after a fixed count of retries.How? Manually – the applet pop-up a box with a URL list of available agents that the user could choose. Manually – the applet pop-up a box with a URL list of available agents that the user could choose. Automatic – the applet automatically redirects the user to a known agent by looking sequentially to the internally managed agent list. If the first agent in the list is passive or unreachable, it tries the next one and so forth … until it founds one that works. Automatic – the applet automatically redirects the user to a known agent by looking sequentially to the internally managed agent list. If the first agent in the list is passive or unreachable, it tries the next one and so forth … until it founds one that works.

Browser Refresh Mechanism When it happens? The agent response contains a string composed of numbers separated by commas. Each number corresponds to an object of the EVA controller. If the string is different from the old string stored by the applet, a refresh is invoked. The agent response contains a string composed of numbers separated by commas. Each number corresponds to an object of the EVA controller. If the string is different from the old string stored by the applet, a refresh is invoked.How? The applet store information about the last received state string text. It compares the new with the old one. If different and the number corresponds to the state parameter of the applet, the applet calls Java appletContext::showDocument() to reload the page. The applet store information about the last received state string text. It compares the new with the old one. If different and the number corresponds to the state parameter of the applet, the applet calls Java appletContext::showDocument() to reload the page.

Conclusion Currently operational and shipped to customers. Currently operational and shipped to customers. Areas of improvement Areas of improvement Use apache as HTTP server rather than proprietary HTTP server called ELM. Use apache as HTTP server rather than proprietary HTTP server called ELM. Dynamically put the applet in browser pages rather than statically through Java servlet. Dynamically put the applet in browser pages rather than statically through Java servlet. Filter non-operational management agent. Filter non-operational management agent. On-the-fly modification of applet parameters. On-the-fly modification of applet parameters.

References cfm?ArticleID= cfm?ArticleID=3568. Vacca, J.R. The Essential Guide to Storage Area Networks. Prentice-Hall, Inc Vacca, J.R. The Essential Guide to Storage Area Networks. Prentice-Hall, Inc Lord, R. Bridge Failover and Page Refresh Mechanism. Sept.9, Lord, R. Bridge Failover and Page Refresh Mechanism. Sept.9, 1999.