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This chapter is from the book

This chapter is from the book

Storage Maintenance Window

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How can access to data in a cloud storage device be preserved during a maintenance outage?

Problem

Hardware maintenance on cloud storage devices can require shutting down the device, resulting in loss of data access and disruption of service.

Solution

An outage prevention system is created to temporarily move the data without interruption during maintenance and other types of outages.

Application

LUN migration is applied to temporarily transfer data to a separate cloud storage device during the maintenance window.

Mechanisms

Cloud Storage Device, Failover System, Resource Replication

Problem

Cloud storage devices subject to maintenance and administrative tasks may need to be temporarily shut down, thereby causing an outage to cloud service consumers and IT resources that require access to the devices and the data they host (Figure 4.31).

Figure 4.31

Figure 4.31 The maintenance task carried out by a cloud resource administrator causes an outage for the cloud storage device. Resultantly, the cloud storage device becomes unavailable to cloud service consumers.

Solution

Prior to a cloud storage device undergoing a maintenance outage, its data can be temporarily moved to a duplicate, secondary cloud storage device. Cloud service consumers are automatically and transparently redirected to the secondary cloud storage device and are unaware that the primary cloud storage device has been taken offline.

Application

Live storage migration is used to convert the data as a whole into an isolated mode and move it to the secondary cloud storage device, as shown in Figures 4.32 to 4.37.

Figure 4.32

Figure 4.32 The cloud storage device is scheduled to undergo a maintenance outage.

Figure 4.33

Figure 4.33 Live storage migration moves the LUNs from the primary storage device to a secondary storage device.

Figure 4.34

Figure 4.34 When the LUN’s data has been migrated, requests for the data are forwarded to the duplicate LUNs on the secondary storage device.

Figure 4.35

Figure 4.35 The primary storage is powered off for maintenance.

Figure 4.36

Figure 4.36 When it is confirmed that the maintenance task on the primary storage device has been completed, the primary storage is brought back online. Live storage migration subsequently restores the LUN data from the secondary storage device to the primary storage device.

Figure 4.37

Figure 4.37 When the LUN migration is completed, all data access requests are forwarded back to the primary storage device.

Mechanisms

  • Cloud Storage Device – This is the primary mechanism to which this pattern is applied.
  • Failover System – Although the migration is often pre-scheduled when this pattern is applied, both manually and automatically initiated failover can be incorporated into this cloud architecture.
  • Resource Replication – The resource replication mechanism is used to keep the primary and secondary storage devices synchronized.
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