Vocabulary Flashcards
What is NAS?
Protocol?
Network Attachment Storage
・storage accessed over a computer network
・Any server that shares its own storage with others on the network and acts as a file server is the simplest form NAS
・protocal: FTP, SMB, CIFS
・a NAS device will have an IP address, and then will be accessible over the network through that IP address.
・NAS appears to a server as a shared folder instead of a shared device over the network.
・ File Level Data access
NAS vs SAN
・NAS is much cheaper than SAN
・SAN is hot-swap
・Mount SAN like a local disk
What is DAS?
Protocol?
Direct-attached storage (DAS) is digital storage directly attached to the computer accessing it, as opposed to storage accessed over a computer network (i.e. network-attached storage)
・protocal: SCSI(Small Computer System Interface), Ethernet, Fiber channel
・normally for heavy and large DAS storage solutions, the media used are SAS(Serially attached SCSI)
What is SAS?
Protocol?
SAS(Serially attached SCSI)
・SAS uses the same SCSI commands to send and receive data from a device.
・If data transfer performance and reliability is the choice, then using SAS is the best solution.
・ 1st generation: 3Gb/s, 2nd generation: 6Gb/s, 3rd generation: 12Gb/s
What is FC?
Protocol?
FC(Fibre Channel)
・Fiber is a term used for any medium used to interconnect in fiber channel protocol. You can even use copper wire for a lower cost.
・Please note the fact that fiber channel standard from ANSI supports networking, storage, and data transfer. Fiber channel is not aware of the type of data that you transfer. It can send SCSI commands encapsulated inside a fiber channel frame(it does not have its own I/O commands to send and receive storage). The main advantage is that it can incorporate widely adopted protocols like SCSI and IP inside.
What is iSCSI?
iSCSI (Internet Small Computer System Interface)
・an IP based standard for interconnecting storage arrays and hosts
・ It is used to carry SCSI traffic over IP networks. This is the simplest and cheap solution(although not the best) to connect to a storage device.
・It does not require special cabling and equipment like the case of a fiber channel network.
・To the system using a storage array with iSCSI, the storage appears as a locally attached disk. This technology came after fiber channel and was widely adopted due to its low cost.
What is SCSI?
SCSI (Small Computer System Interface)
・SCSI is not only used for internal storage but also used for an external storage device to be connected to the server.
What is SATA?
Serial ATA (Serial Advanced Technology Attachment or SATA) is a standard for connecting and transferring data from hard disk drives (HDDs) to computer systems.
Fiber Channel vs iSCSI
・Fiber Channel is much more expensive
・iSCSI has higher latency and lower throughput
・iSCSI is limited and affected by the network traffic
・iSCSI add workload to CPU due to the overhead of IP header
What is SAN?
Protocol?
SAN (Storage Area Network)
・a high-speed network that makes connections between storage devices and servers.
・The server can only access data on the devices, which are directly attached to it.
・hot swap disks
・Good performance/speed
・a block level storage solution
・protocal: Fiber Channel, iSCSI(internal small computer system interface) ※IO protocol: SCSI
・SAN can be considered as a technology that combines the best features of both DAS and NAS.
Encoding
Encoding is for maintaining data usability and can be reversed by employing the same algorithm that encoded the content, i.e. no key is used.
Examples: ascii, unicode, URL Encoding, base64
Encryption
Encryption is for maintaining data confidentiality and requires the use of a key (kept secret) in order to return to plaintext.
Examples: aes, blowfish, rsa
Hashing
Hashing is for validating the integrity of content by detecting all modification thereof via obvious changes to the hash output.
Examples: sha-3, md5 (now obsolete), etc.
Obfuscation
Obfuscation is used to prevent people from understanding the meaning of something, and is often used with computer code to help prevent successful reverse engineering and/or theft of a product’s functionality.
Examples: javascript obfuscator, proguard
