Safeguarding the VTOC Information

Caution – When creating shadow volume sets, do not create shadow or bitmap volumes using partitions that include cylinder 0. Data loss might occur.

The Solaris system administrator must be knowledgable about the virtual table of contents (VTOC) that is created on raw devices by the Solaris operating system. The creation and updating of a physical disk’s VTOC is a standard function of the Solaris operating system. Software applications like the Sun StorEdge Availability Suite, the growth of storage virtualization, and the appearance of SAN-based controllers have made it easy for an uninformed Solaris system administrator to allow a VTOC to be altered inadvertently. Altering the VTOC increases the possibility of data loss.

Remember these points about the VTOC:

■A VTOC is a software-generated virtual table of contents based on the geometry of a device and written to the first cylinder of that device by the Solaris format(1M) utility.

■Various software components such as dd(1M), backup utilities, point-in-time copy software, and remote mirror software can copy the VTOC of one volume to another volume if that volume includes cylinder 0 in its mapping.

■If the VTOC of the source and destination volumes are not identical, some type of data loss might occur. This data loss might not be detected initially, but can be detected later when other utilities are used, like fsck(1M), or when the system is rebooted.

When first configuring and validating volume replication, save copies of all affected devices’ VTOCs using the prtvtoc(1M) utility. The fmthard(1M) utility can be used to restore them later, if necessary.

■When using volume managers like SVM and VxVM, copying between individual volumes created under these volume managers is safe. VTOC issues are avoided because the VTOC is excluded from volumes created by these volume managers.

■When formatting individual partitions on a raw device, for all partitions except the backup partition, make sure the partitions do not map cylinder 0, which contains the VTOC. When using raw partitions as volumes, you are the volume manager and you need to exclude the VTOC from partitions that you configure.

■When formatting the backup partition of a raw device, make sure that the physical geometries of the source and destination devices are identical. (Partition 2, by default, maps all cylinders under the backup partition.) If identical device sizing is not possible, make sure that the source backup partition is smaller than the destination partition and that the destination partition does not map cylinder 0.

Chapter 1 Point-in-Time Copy Software Troubleshooting Tips 3

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Sun Microsystems 3.2 manual Safeguarding the Vtoc Information
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3.2 specifications

Sun Microsystems 3.2, often referred to as SunOS 3.2, was a notable release of the Sun operating system that emerged during the rapidly evolving landscape of computer technology in the early 1980s. This operating platform was designed specifically for Sun Workstations, utilizing the robust hardware architecture developed by Sun Microsystems. The introduction of SunOS 3.2 marked a significant step forward in the development of UNIX-like operating systems optimized for entrepreneurship and scientific applications.

One of the main features of SunOS 3.2 was its adherence to the Berkeley Software Distribution (BSD) model, which allowed for advanced networking capabilities, enhanced performance, and efficient resource management. BSD's influence provided SunOS 3.2 with TCP/IP networking protocols, allowing users to connect to other devices seamlessly and manage network resources easily. This feature was crucial during a time when networking was becoming increasingly vital for organizations.

The system's support for virtual memory was another innovative characteristic. SunOS 3.2 utilized demand paging, which allowed programs to use more memory than was physically installed on their machines, significantly improving multitasking and overall system responsiveness. This capability was particularly advantageous for enterprises that relied on large-scale computations and data analysis.

SunOS 3.2 also introduced support for the Sun Window System, which meant users could utilize graphical user interfaces for interacting with applications, moving away from purely text-based command interfaces. This transition paved the way for more intuitive user experiences in the realm of computing, making powerful UNIX capabilities more accessible.

The inclusion of software utilities such as the C shell (csh) and a variety of development tools further strengthened SunOS 3.2’s position as a suitable platform for developers. The system provided robust development environments for programming in languages like C and assembly, catering to custom application requirements across different industries.

Lastly, security features were integrated into SunOS 3.2 to safeguard sensitive data and enhance system integrity. Permission settings and user authentication mechanisms were refined, allowing organizations to securely manage their computing resources.

In summary, SunOS 3.2 represented a landmark evolution in operating systems, showcasing a blend of advanced networking, memory management, graphical user interface, development tools, and security—elements that defined a generation of computing within the high-performance ecosystem of Sun Microsystems.
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