Data storage term 1: Redundant array of independent
This data protection method is the most popular way to simultaneously store data on multiple hard disks. The main advantage of RAID is that it allows I/O requests to overlap in a way that improves performance when having to copy one set of data to multiple locations.
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- RAID levels and their pros and cons
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Data storage term 2: Storage-area
A SAN is a high-speed, special-purpose network (or subnetwork) that interconnects different kinds of data storage devices with associated data servers on behalf of a larger network of users. A SAN supports special functions such as disk mirroring, backup and restore, archiving and data migration. Fibre Channel is the network protocol most often used for a storage-area network, although Ethernet protocols such as iSCSI have also become viable options for SANs.
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- SAN connectivity between devices
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Data storage term 3: Primary storage
Primary storage refers to storage for data in active use, in contrast to data used for backup or archiving purposes. Primary storage is used for the most frequently accessed data and typically consists of the most expensive storage tiers.
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Data storage term 4: Tiered
Based on levels of protection, performance needs, frequency of usage and other considerations, tiered storage technology assigns various types of data to different storage systems to achieve greater overall efficiency and performance. For example, tier 1 data (mission-critical, recently accessed or classified files) is typically stored on the highest performance drives available, while tier 2 data (infrequently used or less important data) might be located on less expensive hardware.
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- Tips on tiering data storage
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Data storage term 5: Network-attached storage (NAS)
Network-attached storage is an individual network set up around hard disk storage for files. Because NAS isn’t attached to the enterprise application server, storage access and management functions can be carried out at a separate location, allowing multiple computers and processors to handle program and storage requests separately. This results in greater overall I/O performance.
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Data storage term 6: Fibre
Designed to provide high-speed connectivity between servers and storage devices, Fibre Channel connections can deliver speeds of 16 Gbps. Fibre Channel also offers support for devices up to six miles apart. Fibre Channel replaced the Small Computer System Interface (SCSI) protocol for storage networks.
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Data storage term 7: Data
Data dedupe is a data reduction technology. It works by allowing duplicate data to be replaced with a pointer file that redirects applications to the original file stored in a single location. For example, a single 1 megabyte file can take the place of 100 copies of that same 1 megabyte file by substituting 99 pointer files, resulting in potentially enormous capacity savings. This technology is a popular way to reduce capacity requirements for functions like data backup and data archiving, and is emerging as a way to reduce the capacity of primary storage.
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Data storage term 8: Disk striping
Disk striping technology divides data across multiple partitions and disks in computer systems. Striping speeds data retrieval, especially when many drives are used in a RAID scheme. Striping data across multiple hard disks improves performance because it uses hardware in all the drives in parallel. Wide striping spreads chunks of data across multiple arrays, while narrow striping uses a single array to spread data chunks.
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- Using striping technology in RAID systems
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Data storage term 9: Logical unit number (LUN)
A logical unit number uniquely identifies hard disk devices for use with SCSI, iSCSI and Fibre Channel interfaces. LUNs are central to the management of block storage arrays shared over a storage-area network.
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Data storage term 10: Storage
Storage virtualization pools data from multiple physical storage network devices into one virtual location, allowing for easier management and synchronized performance of functions like backup, archiving and recovery. Virtualization can be implemented using software only, appliances or in the storage array.
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This was first published in March 2012