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EspañolDIRECT-ATTACHED STORAGE
(Redirected from Direct Attached Storage)
'Direct-attached storage' (DAS) refers to a digital storage system directly attached to a server or workstation, without a storage network in between. It is a retronym, mainly used to differentiate non-networked storage from SAN and NAS.
The main protocols used in DAS are SCSI, SAS, and Fibre Channel. Traditionally, DAS systems enable storage capacity extension for servers, while keeping high data bandwidth and access rate. Most common DAS Systems are made of one or more enclosures holding storage devices such as hard disks, and one or more controllers. The interface with the server or the workstation is made through a HBA (Host Bus Adapter).
DAS systems typically offer fault tolerance at every level with controller redundancy, cooling redundancy, and storage fault tolerance patterns known as RAID. Entry level DAS systems most often are made of an enclosure without active components such as controllers, thus access logic and fault tolerance patterns are provided by the server HBA.
Middle and top range DAS systems provide embedded controllers. RAID management is off-loaded, and simple non-RAID HBAs can be used, lowering costs. DAS controllers also enable shared storage access, which permits multiple servers (usually no more than 4) to access the same logical storage unit, a feature that is mainly used for clustering. At this point, top range DAS systems share similarities with entry level SAN systems.
DAS has been referred to as "Islands of Information". Disadvantages of DAS include inability to
share data or unused resources with other servers. Both NAS (network-attached storage) and SAN (storage area network) architectures attempt to address this, but introduce some new issues as well, such as higher initial cost, manageability, security, and contention for resources.
★ ATA over Ethernet - a light-weight open source SAN protocol
★ Fibre Channel - the most common SAN protocol
★ InfiniBand - a high-speed interconnect that can be used as a SAN
★ iSCSI - a newer SAN protocol
★ File Area Network
★ Network-attached storage - the most common enterprise storage alternative
★ Redundant array of independent disks (RAID) - a common method of disk storage
★ List of SAN Network Management Systems
★ Centralized storage area networks
★ Distributed storage area networks
★ SMI-S - Storage Management Initiative Specification
'Direct-attached storage' (DAS) refers to a digital storage system directly attached to a server or workstation, without a storage network in between. It is a retronym, mainly used to differentiate non-networked storage from SAN and NAS.
DAS3.jpg
| Contents |
| Features |
| Disadvantages |
| See also |
Features
The main protocols used in DAS are SCSI, SAS, and Fibre Channel. Traditionally, DAS systems enable storage capacity extension for servers, while keeping high data bandwidth and access rate. Most common DAS Systems are made of one or more enclosures holding storage devices such as hard disks, and one or more controllers. The interface with the server or the workstation is made through a HBA (Host Bus Adapter).
DAS systems typically offer fault tolerance at every level with controller redundancy, cooling redundancy, and storage fault tolerance patterns known as RAID. Entry level DAS systems most often are made of an enclosure without active components such as controllers, thus access logic and fault tolerance patterns are provided by the server HBA.
Middle and top range DAS systems provide embedded controllers. RAID management is off-loaded, and simple non-RAID HBAs can be used, lowering costs. DAS controllers also enable shared storage access, which permits multiple servers (usually no more than 4) to access the same logical storage unit, a feature that is mainly used for clustering. At this point, top range DAS systems share similarities with entry level SAN systems.
Disadvantages
DAS has been referred to as "Islands of Information". Disadvantages of DAS include inability to
share data or unused resources with other servers. Both NAS (network-attached storage) and SAN (storage area network) architectures attempt to address this, but introduce some new issues as well, such as higher initial cost, manageability, security, and contention for resources.
See also
★ ATA over Ethernet - a light-weight open source SAN protocol
★ Fibre Channel - the most common SAN protocol
★ InfiniBand - a high-speed interconnect that can be used as a SAN
★ iSCSI - a newer SAN protocol
★ File Area Network
★ Network-attached storage - the most common enterprise storage alternative
★ Redundant array of independent disks (RAID) - a common method of disk storage
★ List of SAN Network Management Systems
★ Centralized storage area networks
★ Distributed storage area networks
★ SMI-S - Storage Management Initiative Specification
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