ckpti-2

ckpti-1ckpti

ckpti+1

n

m

Mappings for block n

m

Filesystem

a.image

p

p

FIGURE 6-2The Copy-On-Write Mechanism for Checkpoints

6.1.2.2Active Checkpoint

Each CFS has a mapping function for all of the blocks on LFS. This mapping function returns a value for each page of LFS. Currently, there can be no more than 16 active checkpoints on a filesystem. This means the checkpoint filesystem can hold at most 16 mappings for each block. Also not all of the blocks in the LFS are mapped. Block allocation table and journaling area are not mapped and checkpointed.

Active checkpoints have a stack-like structure and each checkpoint uses the mapping of itself. If there is no mapping, it will use the mapping for the next checkpoint created after it (this selection of proper mapping is handled by the mapping function). If none of the entries have a mapping, this implies the file system block has never been modified since the creation of oldest checkpoint - in this case the block address will be mapped to itself.

When a new checkpoint is created, a new directory entry is added to the list of checkpoints in checkpoint control page. Also, an available slot in the checkpoint stack is assigned to this newly-created checkpoint. After doing this, the new checkpoint becomes the owner of the corresponding entry in mapping entries for all blocks of the file system. The entire operation is performed in a single transaction and is instantaneous. As soon as a new checkpoint is created, the checkpoint entry becomes available and can be used for all read-only file system operations. There is no partial state visible from other file system users.

6-4Sun StorEdge 5310 NAS Troubleshooting Guide • December 2004

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Sun Microsystems 5310 NAS manual Active Checkpoint, 2The Copy-On-Write Mechanism for Checkpoints
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5310 NAS specifications

Sun Microsystems, known for its innovative computing solutions, launched the Sun 5310 Network Attached Storage (NAS) system, which marked a significant advancement in the realm of storage solutions in the early 2000s. The 5310 NAS was designed to provide high-performance, reliable, and scalable storage tailored for enterprise environments.

One of the standout features of the Sun 5310 NAS is its file-serving capabilities, which support multiple protocols, notably NFS (Network File System) and CIFS (Common Internet File System). This dual-protocol support allowed organizations to seamlessly integrate the NAS into diverse IT ecosystems, facilitating interoperability between UNIX, Linux, and Windows systems. The enhanced file-sharing capabilities made it an ideal solution for businesses with mixed operating environments.

The Sun 5310 NAS incorporates cutting-edge technologies to ensure high availability and data integrity. The system utilized a RAID (Redundant Array of Independent Disks) technology, providing various RAID levels to protect against data loss while optimizing performance. Additionally, the device featured hot-swappable drives, enabling maintenance and upgrades with minimal downtime, a crucial factor for business continuity.

Equipped with advanced management software, the Sun 5310 NAS offered users an intuitive interface for monitoring storage health and performance. This software included comprehensive reporting functionalities that allowed IT administrators to oversee usage patterns and capacity planning efficiently.

Scalability was another defining characteristic of the Sun 5310 NAS. The system could easily expand with additional storage modules, accommodating the growing needs of an organization without the necessity for complete system overhauls. This flexibility ensured that businesses could adapt their storage solutions to meet evolving data storage needs without incurring significant costs or disruptions.

In terms of performance, the Sun 5310 NAS featured high I/O throughput achieved through its robust hardware architecture and optimized file serving capabilities. This performance baseline was crucial for organizations that relied on heavy data workloads and required rapid access to information.

In summary, the Sun 5310 NAS from Sun Microsystems embodied a forward-thinking approach to network storage, blending reliability, scalability, and multi-protocol support. Its user-friendly management software, combined with the robustness of RAID technology and hot-swappable drives, made it a preferred choice for enterprises looking to streamline their storage infrastructure while safeguarding critical data.
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