IT Infrastructure: Storage - Part 1

Flashcards covering key concepts from the IT Infrastructure: Storage Part 1 lecture.

Early Computer Persistent Storage

A storage system using punched cards or paper tape.

Drum Memory

One of the first magnetic read/write storage systems composed of a large rotating metal cylinder coated with magnetic recording material.

IBM RAMAC 350

The first commercial digital disk storage device, part of the IBM RAMAC 350 system, shipped in 1956, storing approximately 5 MB of data on fifty 61 cm diameter disks.

IBM 726

An early magnetic tape system introduced in 1952, storing 2 MB per 20-centimeter-diameter reel of tape.

ATA (Advanced Technology Attachment)

A disk command set primarily used in PCs, employing a relatively simple hardware and communication protocol.

SCSI (Small Computer System Interface)

A disk command set consisting of standards for connecting and transferring data between computers and peripheral devices, commonly used in servers.

Serial ATA (SATA) disks

Low-end, high-capacity disks ideal for bulk storage applications, often used in PCs and laptops, and utilizing the SMART command set.

Serial Attached SCSI (SAS) disks

Relatively expensive, high-end disks with rotational speeds of 10,000 or 15,000 rpm, typically having 25% of the capacity of SATA or NL-SAS disks, and using the SCSI command set.

Near-Line SAS (NL-SAS) disks

Disks that have a SAS interface but utilize the mechanics of SATA disks, often combined with faster SAS disks in one storage array.

Dual Port

A storage device that has two independent data paths to connect to two separate controllers or host systems to provide redundancy and load balancing.

Solid State Drives (SSDs)

Storage drives that don't have moving parts and based on flash technology.

Flash technology

Flash technology is semiconductor-based memory that preserves its information when powered off.

NVMe (Non-Volatile Memory Express)

Drives that can deliver hundreds of thousands of read/write operations and gigabytes of throughput per second.

Kryder's Law

The density of information on hard drives doubles approximately every 13 months.

Tapes

When storing large amounts of data, the most inexpensive option is tape, suitable for archiving

Tape library

A storage device that contains one or more tape drives, a number of slots to hold tape cartridges, a barcode or RFID tag reader, and an automated method for loading tapes.

Virtual Tape Library (VTL)

Uses disks for storing backups. Consists of an appliance or server and software that emulates traditional tape devices and formats.

Controller

A hardware component (sometimes software too) that manages communication between a computer/system and a specific type of device.

LUN (Logical Unit Number)

A logical storage volume that's made available to a host (server) from a storage device (like a SAN or RAID array).

RAID (Redundant Array of Independent Disks)

Solutions that provide high availability of data and improvements of performance using multiple redundant disks. Can be implemented in hardware or software.

RAID 0

Also known as striping. Provides an easy and cheap way to increase performance by using multiple disks.

RAID 1

Also known as mirroring. Is a high availability solution that uses two disks that contain the same data.

RAID 10

Uses a combination of striping and mirroring to provide high performance and availability.

RAID 5

Writes data in disk blocks on all disks and stores a parity block to automatically reconstruct data in case of disk failure.

RAID 6

Protects against double disk failures by using two distributed parity blocks instead of one.

Data deduplication

Searches the storage system for duplicate data segments (disk blocks or files) and removes these duplicates. Used in archived as well as in production data.

Inline deduplication

Checks for duplicate data segments before data is written to disk to avoid duplicate data on disks at any time, which introduces a relatively large performance penalty.

Cloning and snapshots

Making a copy of data at a specific point in time that can be used independently from the source data.

Thin provisioning

Enables the allocation of more storage capacity to users than is physically installed.

Direct Attached Storage (DAS)

A storage system where one or more dedicated disks connect via the SAS or SATA protocol to a built-in controller, connected to the rest of the computer using the PCI bus.

Storage Area Network (SAN)

A specialized storage network that consists of SAN switches, controllers and storage devices to connect a large pool of central storage to multiple servers.

Fibre Channel (FC)

A dedicated level 2 network protocol, specially designed for transportation of storage data blocks.

Fibre Channel over Ethernet (FCoE)

Encapsulates Fibre Channel data in Ethernet packets to allow Fibre Channel traffic to be transported over 10 Gbit or higher Ethernet networks.

Internet Small Computer Systems Interface (iSCSI)

A protocol that allows you to send SCSI commands (used by storage devices) over a TCP/IP network.