Archiving Overview

The Sun Storage Archive Manager (SAM-QFS) software archives files by copying the files from an online disk cache to archive media. The archive media can consist of disk slices in another file system or removable tape or magneto–optical cartridges in automated or manually loaded storage devices. In addition, the Sun SAM 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.

Design Considerations for Archiving

Take the following design considerations into account in the planning and implementation of an archiving environment:

• Access and usage patterns have a significant impact on the tape systems required, including the types of tapes and the number and types of drives and libraries needed. If much staging is anticipated, use linear rather than helical scan tapes.

• The following considerations influence the number of drives and media required:

  • File system sizes and usage patterns: frequency of file updates, average file sizes, batch jobs that will wait for drives/media or users that must have priority

  • Archiving policies: number of media copies, release policies, level of disk over-subscription

  • Media characteristics: size, drive setup times

    For best performance, Fibre Channel tape drives and disk devices should be accessed through separate host bus adapters (HBAs).

If you are managing a server that has the SAM-QFS software installed locally and you are configuring stand-alone file systems on the archiving server, have at least one tape library associated with the current server. The library must contain media of a single media type.

The following table describes archiving configuration guidelines on a per-tape-library basis that can prevent you from overextending your environment.

Table 2-1 Archiving Configuration Guidelines

Your customer requirements drive the maximum number of files in a file system. On an average system, you should be able to restore 100 million files in less than 24 hours. If you do not need to restore files in 24 hours, you can have more files in the file system.

The following considerations can help you avoid overloading your archiving system:

• Tape drives are designed to write large amounts of data at one time, so a well-designed archiving system should reduce the number of loads for the tape drives and increase the amount of data being written at one time.

• If you have only one tape drive with one media type, the startage, startsize, and startcount archive parameters should be set as follows:

  • startage – No less than 8 hours

  • startsize – No less than 50% of the capacity of a single tape, and no more than a TB

  • startcount – A number in the thousands; do not exceed 500,000

    Do not run the recycler more than three times per day.

Design Considerations for File Systems Without Archiving

The Sun QFS software requires a certain amount of disk cache (file system devices) to create and manage data files and directories. An ma type file system requires at least two disk devices or partitions, one for file data and one for metadata. An ms type file system requires only one partition on which both data and metadata are saved. Multiple disk devices or partitions increase I/O performance. See Sun QFS File Systems Design Basics in Sun QFS File System 5.3 Configuration and Administration Guide for a detailed description of the file system types.

The disk devices or partitions do not require any special formatting. You might achieve better performance if you configure multiple devices across multiple interfaces (HBAs) and disk controllers.

The disks must be connected to the server through a Fibre Channel or SCSI controller. You can specify individual disk partitions for a disk, or you can use the entire disk as a disk cache. The software supports disk arrays, including those under the control of volume management software such as Solaris Volume Manager.

Before creating your first file system, you should familiarize yourself with file system layout possibilities. For information on volume management, file system layout, and other aspects of file system design, see Chapter 1, File System Overview, in Sun QFS File System 5.3 Configuration and Administration Guide.