Sun StorEdge SAM-FS Storage and Archive Management Guide

The Sun StorEdge SAM-FS environment provides a configurable file system with storage, archive management, and retrieval capabilities. The Sun StorEdge SAM-FS software archives files by copying the files from online disk cache to archive media. The archive media can consist of disk slices in another file system or it can consist of removable tape or magneto-optical cartridges in automated or manually loaded storage devices. In addition, the Sun StorEdge SAM-FS software automatically maintains online disk space at site-specified usage thresholds. It releases disk space associated with archived file data and restores the files to online disk when they are needed.

This chapter provides a technical overview of the Sun StorEdge SAM-FS components. The following topics are presented:

• Capabilities
• Storage Devices
• Commands

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Capabilities

The Sun StorEdge SAM-FS environment includes a file system and the storage and archive management software. The Sun SAM-QFS environment includes the Sun StorEdge QFS file system. Both file systems are high-performance UNIX file systems that reside in the server's disk cache. The major difference between these file systems is that the Sun SAM-QFS file system offers more high-performance features, including a distributed shared file system. For more information about the file systems themselves, see the Sun StorEdge QFS and Sun StorEdge SAM-FS File System Administration Guide.

The other components that reside in the Sun StorEdge SAM-FS environment are as follows:

• The archiver, which automatically copies online disk cache files to archive media. The archive media can consist of either online disk files or removable media cartridges.
• The releaser, which automatically maintains the file system's online disk cache at site-specified percentage usage thresholds by freeing disk blocks occupied by eligible archived files.
• The stager, which restores file data to the disk cache. When a user or process requests file data that has been released from disk cache, the stager automatically copies the file data back to the online disk cache.
• he recycler, which clears archive volumes of expired archive copies and makes volumes available for reuse.

The following sections briefly describe each of these capabilities. You can find more information about these capabilities in subsequent chapters.

Archiving

By default, the archiver automatically creates one archive copy of all files in a Sun StorEdge SAM-FS file system and it writes the archive copy to archive media. You can configure the archiver to create up to four archive copies on a variety of archive media. If a file is segmented, each segment is treated as a file, and each segment is archived separately. The archiving process is initiated after disk-based files match a site-definable set of selection criteria.

For more information about the archiver, see Archiving. For more information about segmented files, see Segmented Files.

Releasing

Releasing is the process of freeing primary (disk) storage that is used by an archived file's data. Two threshold values, both expressed as a percentage of total disk space, are used to manage online disk cache free space. These thresholds are the high water mark and the low water mark. When online disk consumption exceeds the high water mark, the system automatically begins releasing the disk space occupied by eligible archived files. Disk space occupied by archived file data is released until the low water mark is reached. Files are selected for release depending on the file's size and age. Optionally, the first portion of a file can be retained on disk for speedy access and for masking staging delays. If a file has been archived in segments, portions of the file can be released individually. For more information about the releaser, see Releasing.

Staging

When a file whose data blocks have been released is accessed, the stager automatically stages the file or file segment data back to online disk cache. The read operation tracks along directly behind the staging operation, allowing the file to be immediately available to an application before the entire file is completely staged.

The Sun StorEdge SAM-FS software processes stage request errors automatically. If a stage error is returned, the system attempts to find the next available archive copy of the file. Stage errors that can be automatically processed include media errors, unavailability of media, unavailability of an automated library, and others. For more information about staging, see Staging.

Recycling

As users modify files, archive copies associated with the old versions of these files are considered to be expired on their archive media. Such copies are no longer needed, so they can be purged from the system. The recycler identifies the archive volumes with the largest proportions of expired archive copies and preserves the nonexpired copies by moving them to separate volumes.

If a removable media volume contains only expired copies, you can take one of the following actions:

• You can relabel the volume for immediate reuse.
• You can export the volume to offsite storage as an historical record of file changes. You can use standard UNIX utilities to restore previous versions of files from expired archive copies.

The recycling process is transparent to end users as it relates to their data files. For more information about recycling, see Recycling.

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Storage Devices

The Sun StorEdge SAM-FS environment supports a wide variety of tape storage and magneto-optical devices. The automated libraries that Sun StorEdge SAM-FS supports can be divided into the following groups depending on how they are attached to the environment:

• A direct attachment. A direct-attached library is connected directly to the host system using a small computer system interface (SCSI). This can be either a direct connection or a Fibre Channel connection. For example, a direct attachment is used for Sun StorEdge libraries. The Sun StorEdge SAM-FS system controls these libraries directly using the SCSI standard for automated libraries.
• A network attachment. The Sun StorEdge SAM-FS software can be configured as a client of the library's host system. The network-attached libraries include some of the StorageTek, ADIC/Grau, IBM, and Sony libraries. These libraries use a software package supplied by the vendor. In these cases, the Sun StorEdge SAM-FS software interfaces with the vendor software using a daemon specifically designed for the automated library.

TABLE 1-1 shows the daemons specific to various automated libraries.

For a list of supported storage devices, contact your Sun Microsystems sales representative or your authorized service provider (ASP).

The relationships between the devices managed within the Sun StorEdge SAM-FS environment are defined in the master configuration file, /etc/opt/SUNWsamfs/mcf. The mcf file specifies the removable media devices, libraries, and file systems included in the Sun StorEdge SAM-FS environment. Each piece of equipment is assigned a unique equipment identifier in the mcf file. Entries in the mcf also define manually mounted archiving devices and automated library catalog files.

When possible, the system uses the standard Solaris disk and tape device drivers. For devices not directly supported in the Solaris operating system (OS), such as certain library and optical disk devices, special device drivers are included in the Sun StorEdge SAM-FS software packages.

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Commands

The Sun StorEdge QFS and Sun StorEdge SAM-FS environments consist of a file system, daemons, processes, various types of commands (user, administrator, and so on), and tools. This section describes the commands that are included in the Sun StorEdge QFS and Sun StorEdge SAM-FS software distributions.

The Sun StorEdge QFS and Sun StorEdge SAM-FS commands operate in conjunction with the standard UNIX file system commands. Some commands are specific to only one product. All the commands are documented in UNIX man(1) pages.

The Sun StorEdge QFS and Sun StorEdge SAM-FS File System Administration Guide contains overview information for the daemons, but individual daemons are described throughout the documentation set where appropriate.

This section introduces the commands and indicates which commands you can use within the Sun StorEdge QFS or Sun StorEdge SAM-FS file systems. See the man pages that are included in the software distribution for more information.

This section contains the following topics:

• User Commands
• General System Administrator Commands
• File System Commands
• Automated Library Commands
• Archiver Commands
• Specialized Maintenance Commands
• Site-Customizable Scripts
• Application Programming Interface
• Operational Utilities

User Commands

By default, file system operations are transparent to the end user. Depending on your site practices, however, you might want to make some commands available to users at your site to fine-tune certain operations. TABLE 1-2 summarizes these commands.

General System Administrator Commands

TABLE 1-3 summarizes the commands that you can use to maintain and manage the system.

File System Commands

TABLE 1-4 summarizes the commands that you can use to maintain the file system.

Automated Library Commands

TABLE 1-5 summarizes the automated library commands that you can use to configure, initialize, and maintain the automated libraries and devices within the Sun StorEdge SAM-FS environment.

Archiver Commands

TABLE 1-6 summarizes the commands that control the archiver's actions within the Sun StorEdge SAM-FS environment.

Specialized Maintenance Commands

TABLE 1-7 summarizes the various maintenance commands you can use in a Sun StorEdge SAM-FS environment.

Site-Customizable Scripts

TABLE 1-8 summarizes the site-customizable scripts that you can use to monitor and control the Sun StorEdge SAM-FS environment. By default, the software installs these scripts in /opt/SUNWsamfs/examples. You can move these scripts from /opt/SUNWsamfs/examples to /etc/opt/SUNWsamfs/scripts and modify them to perform the desired action for your site. For more information about these scripts, see their respective man pages.

Application Programming Interface

You can use the application programming interface (API) to make file system requests from within a user application. The requests can be made locally or remotely to the machine on which the file system is running. The API consists of the libsam and libsamrpc libraries. These libraries contain library routines for obtaining file status; for setting archive, release, and stage attributes for a file; and for manipulating the library catalog of an automated library. The sam-rpcd remote procedure call daemon handles remote requests. To automatically start the sam-rpcd daemon, set samrpc=on in the defaults.conf file.

For more information about the API, see the intro_libsam(3) man page. This man page provides overview information for using the library routines in libsam and libsamrpc.

Operational Utilities

Within the Sun StorEdge SAM-FS environment, you can use the samu(1M) operator utility and SAM-QFS Manager to perform basic operations. TABLE 1-9 summarizes the operational tools.

Sun StorEdge SAM-FS Storage and Archive Management Guide

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Copyright © 2004, Sun Microsystems, Inc. All rights reserved.