GLOSSARY
D
dk
Media type identification for hard disk media or diskarchive. The dk flag indicates that the file is on fast disk archive, providing almost immediate access. According to actual archive policies, files smaller than 128MB go automatically on diskarchive. This way the average access time is higher than if it were stored on tape. Nevertheless larger directories containing many small files should be archived with tar or zip.
F
File Transfer Protocol (FTP)
The File Transfer Protocol is a standard network protocol used to exchange and manipulate files over an internet protocol computer network.
FTP is built on a client-server architecture and utilizes separate control and data connections between the client and server applications.
FTP includes functions to log onto the network, list directories and copy files. FTP operations can be performed by typing commands at a command prompt or via an FTP utility running under a graphical interface.
FTP transfers can also be initiated from within a Web browser by entering the URL preceded with ftp://.
FTP is also often used as an application component to automatically transfer files for program internal functions.
H
Hierarchical Storage Management (HSM)
Hierarchical Storage Management (HSM) is a data storage system that automatically moves data between high-cost and low-cost storage media. HSM systems exist because high-speed storage devices, such as hard disk drives, are more expensive (per byte stored) than slower devices, such as optical discs and magnetic tape drives. While it would be ideal to have all data available on high-speed devices all the time, this is prohibitively expensive for many organizations. Instead, HSM systems store the bulk of the enterprise's data on slower devices, and then copy data to faster disk drives when needed. In effect, HSM turns the fast disk drives into caches for the slower mass storage devices. The HSM system monitors the way data is used and makes best guesses as to which data can safely be moved to slower devices and which data should stay on the hard disks. The advantage is that the total amount of stored data can be much larger than the capacity of the disk storage available.
L
li
Media type identification for LTO4 media.
High capacity (800GB), fast transfer (120MB/s) and slow access time (~ 1.5min) tape cartridges.
N
Network File System (NFS)
A network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed.
NcFTP
The NcFTP Client, also known as just NcFTP, is a set of free application programs implementing the File Transfer Protocol (FTP). It can be downloaded from the NcFTP website.
NIS
The Network Information Services is a naming service originally developed by Sun Microsystems that allows resources to be easily added, deleted or relocated. Formerly known as Yellow Pages or YP, NIS is a de facto Unix standard.
S
SamFS (SAM/QFS)
The Storage and Archive Management File System. An HSM implementation originally developed by LSC, later acquired by Sun Microsystems.
sf
Media type identification for Sun-StorageTek 9940B media. Capacity 200GB, transfer rate 30MB/s and access ~1min tape cartridges.
sg (decommissioned)
Media type identification for StorageTek 9840 media. Those are 20GB low capacity, 10MB/s slow transfer rate and fast access (~ 20sec) tape cartridges.
stage
The process of bringing the files from a nearline storage media, as the diskarchive or tape cartridge, to the online disk cache in order to access file's data.
The most useful options are:
-r recursive directory tree stage
-w wait for each file to be staged back on-line before completing
"man stage" on bar or on archive system "ssh bar.cscs.ch man stage"