Battery Backup Unit

Each RAID controller contains a three-cell lithium-ion battery backup unit (BBU) that powers the controller’s cache memory and preserves the cache contents in the event of a power outage of up to

72 hours. The RAID controller firmware performs a test of the BBU at startup and will illuminate the battery fault LED if the battery is not operating within specified ranges, or if the battery is missing. For a description of the battery fault LED, see Table 1-5. For information on removing and installing the BBU, see "Removing and Installing a RAID Controller Module Backup Battery Unit" on page 60.

NOTE: For virtual disks, the RAID controller firmware changes the data cache setting based on the state of the battery. If the battery is missing or does not have sufficient charge, the controller flushes the cache and sets the write cache attribute to Write Through for all virtual disks. When the battery is replaced, Write Back is reenabled.

The RAID controller module logs the age of the battery and issues a replacement reminder message approximately six weeks before expiration. After replacing the battery, you must use MD Storage Manager to reset the battery age.

RAID Enclosure Thermal Shutdown

Enclosure management provides a feature that automatically shuts down the enclosure when the temperature within the storage enclosure exceeds a safe threshold. Thermal shutdown protects the data on the physical disks from corruption in the event of cooling system failure. It is not necessary to shut down any expansion enclosures attached to the storage enclosure.

The enclosure temperature probe’s Nominal Failure Threshold and Maximum Failure Threshold determine the temperature at which shutdown occurs. These thresholds are default settings that cannot be changed. If the temperature sensors on the backplane or RAID controller module detect a temperature exceeding the Nominal Failure Threshold, a critical event is set; if the Maximum Failure Threshold is hit, shutdown of the enclosure power supplies occurs within 5 seconds.

Cache Functions and Features

Cache Mirroring

The cache mirroring function copies accepted host-write data from the primary controller to the partner controller. This action ensures that host-write data is safely mirrored to the partner controller before successful completion status is returned to the host. If a controller fails, the surviving controller safely retains all mirrored data. Cache mirroring is enabled by default.

Write-Back Cache

Write-back cache is a caching strategy whereby write operations result in a completion signal being sent to the host operating system as soon as the cache receives the data to be written. The target physical disk will receive the data at a more appropriate time in order to increase controller performance. In dual- active controller configurations with write-back caching enabled, the write data is always copied to the cache of the second controller before completion status is issued to the host initiator. Write Back is enabled by default.

About Your System

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Dell MD3000 owner manual Cache Functions and Features, Battery Backup Unit
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MD3000 specifications

The Dell MD3000 is a renowned storage area network (SAN) solution recognized for its flexibility, scalability, and high performance. Designed to meet the demands of small to medium-sized businesses (SMBs) and enterprise environments, the MD3000 offers a plethora of features that enhance data management and storage capabilities.

One of the standout features of the MD3000 is its modular design. This allows users to start with a basic configuration and expand their storage capacity as their needs grow. The system can support up to 30 drives, including both SATA and SAS drives, giving users the ability to optimize cost and performance based on their specific requirements. With support for a diverse range of drive types, the MD3000 ensures that businesses can implement a storage solution that aligns perfectly with their performance and budgetary needs.

The MD3000 leverages advanced technologies to deliver exceptional performance and reliability. It is equipped with Intelligent Disk Pools that optimize the allocation of data across drives, ensuring improved access speeds and overall system efficiency. This dynamic management of data not only enhances performance but also extends the lifespan of the storage devices.

Data protection is another critical component of the MD3000. The system features various RAID configurations, allowing users to choose the level of redundancy that suits their operational requirements. Additionally, robust snapshot capabilities help businesses create point-in-time copies of their data, enabling quick recovery in case of data loss or corruption.

Connectivity options are abundant with the MD3000. It supports both iSCSI and Fibre Channel, providing users the flexibility to integrate it seamlessly into existing network infrastructures. This adaptability makes it an attractive option for organizations looking to modernize their storage systems without overhauling their entire architecture.

Furthermore, the MD3000 is equipped with a user-friendly management interface. The GUI enables quick provisioning and monitoring of storage resources while providing insightful analytics and alerts, allowing IT teams to maintain optimal performance with ease.

In summary, the Dell MD3000 is a highly versatile and efficient storage solution that meets diverse organizational needs. Its scalable architecture, advanced features, and strong support for data protection and management make it an ideal choice for businesses aiming to enhance their storage capabilities while ensuring reliability and performance. Whether for virtualization, database management, or general storage needs, the MD3000 stands out as an excellent investment in enterprise storage technology.
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