HP-UX System Administrator's Guide: Overview HP-UX 11i v3 (B3921-90011, September 2010)

tmp files are not usually removed during system startup, but when
(or whether) files in either of the tmp directories are removed is
configurable and installation specific.
Storage on HP-UX
Of all the resources managed by any operating system, arguably the most important is storage.
Storage is a generic term referring to devices that store data. Storage can take many forms,
including:
• Physical disk drives locally attached to a server:
— SCSI hardware protocol disks
— Fibre Channel disks
— USB 2.0 disks
• Drive enclosures containing multiple physical disks locally attached to a server
• Disk arrays (drive enclosures as with the previous item but with a disk controller added to
the enclosure to manage disks within the enclosure) attached locally to a server (sometimes
called JBODs—for Just a Bunch Of Disks—and sometimes called RAIDs—for Redundant
Arrays of Inexpensive Disks)
• Storage Area Networks (SANs), physical disks or disk arrays as above, but configured and
accessed through a special high speed network. SAN storage can be physically near the
servers accessing it or physically distant for disaster protection. Storage Area Networks
work at the block I/O layer, below the file system layer.
• Network Attached Storage (NAS), an alternate network storage solution, working at the file
system layer using standard network protocols (NFS, CIFS)
• Off line storage or removable media. Data are stored on:
— Tapes (DLT, DDS, Reel, and other tape formats)
— Optical Media (CD, Magneto-optical, DVD-ROM, and other optical formats)
— Removable disk drives
Offline storage is often used for off site storage of data (usually backups) for purposes of
disaster recovery.
Storage Uses
In the HP-UX operating system, storage can be used in many ways; among them:
• Files and Directories stored locally in file systems
• Databases stored on disk volumes in raw form (managed by the database application rather
than by HP-UX) for speed
• Swap space (used by HP-UX for paging purposes)
• Dump space (used to capture the state of HP-UX following a system panic or other significant
event)
How Storage is Organized
Like networking and many other subsystems in the computing world, storage is comprised of
many layers, from the physical devices to the applications that read and write data to those
devices. Collectively these layers are known as the storage stack.
The following sections cover the various components of the HP-UX storage stack.
Physical Storage Devices
At the lowest level of the storage stack are the physical devices that store and retrieve data.
Usually these are disk drives, but they can be other storage devices as well, including:
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