Lesson 11

This module introduced you to Linux tools designed to help you protect against loss of data. You learned that Red Hat Linux supports tape drives for use as backup devices. SCSI (Small Computer System Interface) hardware, particularly in forms like DAT (Digital Audio Tape) and DDS (Digital Data Storage) tape drives, is generally considered deprecated or legacy hardware in modern computing environments. Here’s why:

1. Age and Slow Data Transfer Rates
   • SCSI technology, especially in older formats like DAT and DDS, was developed decades ago. These interfaces typically have slower data transfer rates compared to modern storage interfaces like SATA, SAS, and NVMe.
   • While some SCSI standards can support reasonable speeds, the older DAT and DDS formats are slower and less efficient by today’s standards.
2. Limited Support
   • Many modern operating systems and hardware manufacturers have dropped direct support for SCSI in favor of newer standards, making it challenging to find compatible parts, drivers, or support.
   • Server-grade systems and high-end workstations have moved towards SAS (Serial Attached SCSI) for faster, more reliable storage.
3. Alternative Storage and Backup Technologies
   • The rise of cloud storage, external hard drives, SSDs, and other high-speed, high-capacity media has largely displaced DAT/DDS tape systems for data backup and storage.
   • For long-term archival storage, newer technologies such as LTO (Linear Tape-Open) tapes are more commonly used and offer higher storage capacities and speeds, with longer support lifecycles.
4. Physical Size and Power Requirements
   • SCSI hardware, especially in older formats, often requires large, power-hungry devices that are bulky by today’s standards. Compact, energy-efficient storage solutions have become the norm.
5. Maintenance and Media Availability
   • SCSI DAT and DDS media can be difficult to source, and the drives themselves often require more maintenance than modern alternatives, making them impractical for most contemporary uses.

While some legacy systems might still use SCSI for compatibility or specific archival needs, DAT and DDS SCSI tape drives are largely obsolete. Most organizations have transitioned to more modern storage solutions that offer better performance, reliability, and support.

mt tape operations including rewind, offline, and erase are used to manipulate these drives. Next, you learned about the tar, dump, and restore commands. The tar command creates archives and extracts files and directories from tar archives. The dump command offers a more extensive set of backup options by allowing incremental as well as full dumps to be performed. The restore command is a companion to dump and is used to recover file systems that have been backed up using the dump command. Finally, you learned about RAID. RAID is a powerful tool to protect data from loss and inaccessibility. Various levels of RAID are available for use. The need for data redundancy, availability, and the amount of disk space and spare disks determine what level of RAID is appropriate. RAID 1 (mirroring) and RAID 5 (striping and parity) are the levels most commonly used. Cost and performance issues affect the selection of hardware or software RAID. Hardware RAID improves processing performance by carrying out some of the calculations needed for its operation; however, it is more expensive.
Having completed this module, you should be able to:

1. List the kinds of tape-drive hardware supported by Linux
2. Recognize tape control commands
3. Use the tar command to back up and restore files and directories
4. Use the dump command to back up file systems
5. Use the restore command to recover file systems
6. List tape backup applications available from Red Hat
7. Explain basic concepts related to RAID
8. Describe RAID levels
9. Compare and contrast hardware and software RAID

This module introduced you to the following terms:

1. ATAPI/IDE: ATAPI (AT Attachment Packet Interface) is a standard for connecting CD-ROM and tape backup drives to your computer via a standard hardware interface, and is part of the Enhanced IDE. Generally, IDE (Integrated Drive Electronics) is used as an interface to address hard disk drives.
2. Mirroring: Mirroring uses n partitions that all store the same data for data redundancy and decreased read time.
3. Parity: Parity is the calculation of an additional stripe from the normal data stripes, to be used to recover lost data in the event of a drive failure.
4. QIC-80: QIC 80 is a tape standard that can be used to determine which tapes or devices will work with a particular operating system or backup utility.
5. SCSI: Small Computer Systems Interface is a standard for connecting peripherals to your computer via a standard hardware interface.
6. Striping: Striping is the arrangement of contiguous disk blocks across multiple drives instead of within the same drive. Striping is intended to increase the efficiency of disk access by allowing concurrent seeks on multiple devices.

The next module discusses how to administer local file systems.

Before moving on to the next module, click the Quiz link below to test your understand of how to protect against loss of data.
Protecting Against DataLoss - Quiz