Chapter 7: Technology Background

Predictive Data Migration (PDM)

Predictive Data Migration (PDM) is the migration of data from the suspect disk drive to a spare disk drive, similar to Rebuilding a Logical Drive. But unlike Rebuilding, PDM constantly monitors your disk drives and automatically copies your data to a spare disk drive before the disk drive fails and your Logical Drive goes Critical.

After the data is copied from the suspect disk drive, the controller marks it with a Stale configuration and a PFA error.

You can clear the Stale configuration and PFA error and put the disk drive back into service. See “Clear Physical Drive Conditions” on page 89 for WebPAM PROe or see “Clear Stale and PFA Conditions” on page 139 for the CLU. In most cases, however, you will remove the disk drive for repair or replacement.

PDM Triggers

The following actions trigger PDM:

A disk drive with unhealthy status (see below)

Media Patrol finds a disk critical error*

You initiate PDM manually

*PDM also counts the number of media errors reported by Media Patrol.

A disk drive becomes unhealthy when:

A SMART error is reported

The bad sector remapping table fills to the specified level

Because data would be lost if written to a bad sector, when a bad sector is detected, the disk drive creates a map around it. These maps are saved in the bad sector remapping table, which has a capacity of 512 reassigned blocks and 1024 error blocks.

When the table fills to a specified percentage of its capacity, PDM triggers a migration of data from the suspect drive (the disk drive with the bad sectors) to a spare disk drive.

During data migration, you will have access to the Logical Drive but it will respond more slowly to read/write tasks because of the additional operation. The time required for data migration depends on the size of the disk drive.

See “Logical Drive PDM” on page 110.

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Promise Technology m210p, m310p, VTrak external disk array subsystem manual Predictive Data Migration PDM, PDM Triggers

m210p, VTrak external disk array subsystem, m310p specifications

Promise Technology has established itself as a strong player in the storage solutions market, particularly with its VTrak series of storage systems. Among the notable products in this lineup are the VTrak M310P and M210P models, designed to deliver efficiency, scalability, and high performance for businesses of all sizes.

The Promise VTrak M310P is a high-performance storage solution that emphasizes speed and versatility. This model supports both SAS and SATA drives, enabling enterprises to tailor their storage needs based on workload requirements. It is built with an advanced RAID engine that provides multiple RAID levels, including RAID 0, 1, 5, 6, 10, 50, and 60, ensuring data redundancy and protection against drive failures. The M310P can accommodate up to 96TB of raw storage when fully populated, catering to environments that require large amounts of data retention and quick access times.

Key features of the VTrak M310P include the intuitive management interface, which simplifies storage provisioning and monitoring. This model also incorporates Promise's innovative "HyperRAID" technology, which enhances performance by optimizing I/O operations and providing real-time analytics and reporting. Additionally, the M310P supports a variety of host connection interfaces, including iSCSI, Fibre Channel, and InfiniBand, allowing seamless integration into existing infrastructure.

On the other hand, the VTrak M210P is tailored for a slightly different audience, focusing on small to medium-sized businesses that require reliable and cost-effective storage solutions. The M210P retains several high-end features found in its bigger counterpart while offering a more budget-friendly option. This model also supports a mix of SAS and SATA drives and includes RAID capabilities similar to the M310P for data protection.

The M210P provides a robust set of management tools designed for ease of use, including automated alerts and comprehensive reporting capabilities. Its compact design and reliable performance make it ideal for remote office locations or data centers where space is a premium. Furthermore, the model incorporates advanced power management features to reduce energy consumption without compromising performance.

Both the M310P and M210P are built with scalability in mind, allowing businesses to easily expand their storage capacity as data needs grow. With a focus on durability, performance, and advanced technology, Promise Technology’s VTrak systems are well-positioned to meet the evolving demands of modern data storage. Whether for large enterprises or smaller organizations, these products offer solutions that enhance productivity and ensure data integrity.