Storage Networks

Basics and Applications of Fibre channel SAN (Storage Area Network), NAS (Network attached storage), ISCSI (Internet Small Computer System Interface), Infiniband and FCoE (Fibre channel over Ethernet).

Disk Subsystem (visualised as  Hard disk server): A disk subsystem is a storage subsystem that supports only disk devices. A disk subsystem is a type of disk array, or a type of disk storage, that contains an integrated collection of disk drives, plus any required control software. As with other sorts of disk array, a disk subsystem provides storage services to a set of computers.

Disk Subsystems provides block-oriented storage.

Standard I/O Techniques: SCSI, Fibre Channel, Increasingly Serial ATA(SATA) and Serial attached SCSI(SAS)

I/O Channels: I/O channels can be designed with built-in redundancy in order to increase the fault-tolerance of a disk subsystem.

1. Active
2. Active/Passive
3. Active/Active (No load sharing)
4. Active/Active (Load Sharing)

Disk Subsystems that support RAID (Redundant Array of Inexpensive Disks/Redundant Array of Independent Disks) are called RAID Arrays.

RAID has 2 main goals: 1. Increase performance by stripping 2)  Increase fault-tolerance by redundancy

NAS( Network attached storage) is the name for preconfigured file servers. They consist of one or more internal servers, preconfigured disk capacity and a stripped-down or special OS.

Storage Virtualisation:
The objectives of the storage virtualisation are,

1. Simplification of the administration and access of storage resources.
2. Full utilization and possibilities of storage network
3. Realization of advanced storage functions.

NFS - Network File systems
CIFS - Common Internet File systems

Difference between snapshots and instant copies

posted Feb 26, 2012, 6:24 AM by Sachchida Ojha   [ updated Feb 26, 2012, 6:24 AM ]

                                              Instant Copy                                                                          Snapshot
Place of realisation                    Disk Subsystem                                                                   File System
Resource Consumption              Loads disk subsystem's, controller and its buses.                   Loads server's CPU and all buses
Availability                                Depends upon disk subsystems                                             Depends upon File system
                                                (Hardware-dependent)                                                            (Hardware-independent)

File Systems

posted Feb 26, 2012, 6:05 AM by Sachchida Ojha   [ updated Feb 26, 2012, 6:14 AM ]

File systems form an intermediate layer between block-oriented hard disks and applications, with a volume manager often used between the file system and the hard disk.

To increase the performance, databases can get around the file system and manage the block themselves.

File system <---------------------------Directories and Files
Volume Manager  <-----------------------Logical Blocks

Modern File systems provides 3 functions

1. Journaling -> Mechanism that guarantees the consistency of the file system even after the system crash.
2. Snapshots and -> Same as instant copies  function of disk subsystems.
3. Dynamic file system expansion ->

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