Or one or more drives in the array have failed in a

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Or one or more drives in the array have failed. In a RAID 0 configuration, this can be catastrophic as the data is striped across all of the drives in the array. A loss of a disk means all of its data stripes are lost. In this situation you must replace the failed disk, rebuild the array and then restore the data from backup. RAID levels that include redundancy such as RAID 1, RAID 5, RAID 1+0, and RAID 0+1 can tolerate disk failures better. Usually you can simply replace the failed disk and then wait for the datato be automatically restored from the other disks in the array, using mirroring or parity. Summary 8:37-8:46 In this lesson, we reviewed several common storage issues you may encounter as a PC technician. We talked about improving slow performance and troubleshooting boot failures, drive errors and basic RAID issues. Several commonly observed issues with storage devices are shown here. Be aware that this lesson cannot cover every storage issue and its cause. Instead, several of the more common issues and their causes are addressed. For more complex issues, use all of the resources available in order to identify the problem. This includes the following: System docs Knowledge bases Service manuals User forums When troubleshooting storage drives, it is important to know the type of drive you are working with. There are two main types of storage drives that are used in computers: mechanical hard disk drives (HDDs) and solid state hard drives (SSDs). Mechanical hard disks have moving parts that wear out over time. It's not a matter of if an HDD will fail, it's a matter of when it will fail. SSDs don't have any moving parts, but the storage medium they use has finite read/write counts. The more use an SSD gets, the faster it will wear out. All storage devices have a Mean Time Between Failure (MTBF) rating that is an estimated lifespan for the device. Because of the sealed nature of storage devices, there's really no maintenance you can perform. Instead, you need to decide when it is time to replace the disk. Accordingly, you should implement a data backup plan for your hard disks to ensure the data on them is protected in the event of a failure. Some common storage device issues and associated resolutions are listed in the following table: Issue Device Type Resolution Slow performance HDD Several things can help increase the performance of a slow HDD: Maintain a healthy amount of free disk space on the drive. A mostly empty disk runs faster than a mostly full disk. If a disk is getting full, migrate to a newer, bigger disk. Keep the disk defragmented. A heavily fragmented disk can run quite slowly. You'll need ample free space to fully defragment the drive. Check the disk rotational speed. A disk that spins faster will perform better. Check the speed of the disk interface. If your system uses an older disk interface, upgrade to a faster interface (if possible).
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SSD The more an SSD is used, the slower the read/write speed will be.
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