Recovering from Disk Problems

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If you are unable to avoid a disk problem, a variety of tools can help you recover, depending on the problem you are facing . Recovering from system misconfigurations, load imbalances, and disk failures is discussed in this section.

Many tools and techniques are available to help correct a disk load imbalance after it is discovered . Frequently accessed files and swap areas can be spread over different filesystems, spindles, and disk controllers. Disk striping and LVM can be used to spread access across multiple disks. LVM stripe sizes are defined when logical volumes are created. You need to understand I/O access patterns so that you can set the appropriate stripe sizes. More disks may need to be added so that the load can be spread out effectively.

You may want to dedicate disks to a single application to avoid contention problems. A more drastic solution to a performance problem may be to move an application and its data to another system, on which it may have more exclusive access to system resources, including CPU and memory. In some cases, you may be able to study and redesign an application to make fewer disk I/Os.

As long as you have been making regular system backups , you should be able to recover without a loss of data.

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