Uptime is a measure of the time a computer system has been "up" and running. Measurement is the process of estimating the magnitude of some attribute of an object such as its length or weight relative to some standard ( unit of measurement) such as In Computer science and Computer programming, system time represents a computer system's notion of the passing of Time. A computer is a Machine that manipulates data according to a list of instructions. It came into use to describe the opposite of downtime, times when a system was not operational. Downtime or outage refers to a period of time or a percentage of a timespan that a System is unavailable or Offline. The uptime and reliability of computer and communications facilities is sometimes measured in nines (similar to the unit of metallic purity). Nines are an informal yet common method of grading the purity of very fine precious metals such as Platinum, Gold and Silver. "Five nines" means 99. 999% availability, which translates to a total downtime of approximately five minutes and fifteen seconds per year.

It is often used as a measure of computer operating system reliability and stability, in that this time represents the time a computer can be left unattended without crashing, or needing to be rebooted for administrative or maintenance purposes. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination A crash in Computing is a condition where a program (either an application or part of the Operating system) stops performing its expected function and also ReBoot is a Canadian CGI - animated action-adventure Television series that originally aired from 1994 to 2001 Long uptime can also indicate negligence as many critical updates require reboot on some operating systems.

The uptime(1) command on Unix systems will show the current time, the uptime, the number of users and load averages for the past 1, 5 and 15 minute intervals. Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer In UNIX Computing, the system load is a measure of the amount of work that a computer system is doing

$ uptime
10:52PM  up 1337 days,  7:45, 3 users, load averages: 0. 21, 0. 24, 0. 23

The Uptime-Project, until 1 March 2007, collected data on uptimes from users, and the current record for longest uptime is 11 Years 303 Days 20 Hours 57 Minutes on a computer running OpenVMS. Open Virtual Memory System ( OpenVMS) initially known just as Virtual Memory System ( VMS) is the name of a High-end Computer server Rumours mention in January 2008 that Irish Rail had an OpenVMS machine up for 18 years^[1], and restarted just for Y2K tests. rail transport in Ireland Iarnród Éireann ( IÉ;; in English, Irish Rail) is the national Railway system operator of the Republic The Year 2000 problem (also known as the Y2K problem, the millennium bug, the Y2K bug, or simply Y2K) was a notable Computer bug resulting The uptime of a personal computer is sometimes displayed as a badge of honour on an email signature or web site/forum. A signature block (often abbreviated as signature, sig block, sig file,. This was especially true in the Windows 9x days, where Windows NT and Windows 2000 users would boast of uptimes of more than 30 days, whereas many real-world Windows 9x installations crashed more often. Windows 9x is the family of Microsoft Windows Operating systems that comprises the hybrid 16/32-bit Windows versions Windows 95, Windows 98 Windows NT is a family of Operating systems produced by Microsoft, the first version of which was released in July 1993 Windows 2000 (also referred to as Win2K) is a preemptive, interruptible graphical and business-oriented Operating system designed to work with In more recent times very long uptimes for home users with Windows NT and Windows 2000 machines are less striking because the Windows 9x line has been replaced by the Windows NT-based Windows XP. Windows XP is a family of 32-bit and 64-bit Operating systems produced by Microsoft for use on Personal computers including home and

Netcraft maintains the uptime records for many thousands of web hosting computers. Netcraft is an Internet services company based in Bath, England.

Users of Windows XP Professional, Windows Server 2003 and Windows Vista systems can type systeminfo at the Command Prompt to display all system information, including the System Up Time. Windows XP is a family of 32-bit and 64-bit Operating systems produced by Microsoft for use on Personal computers including home and Windows Server 2003 (also referred to as Win2K3 is a server Operating system produced by Microsoft. Windows Vista (ˈvɪstə is a line of Operating systems developed by Microsoft for use on Personal computers including home and business desktops cmdexe is the Command line interpreter on OS/2, Windows CE and on Windows NT -based operating systems (including Windows

systeminfo | find "Up Time"
System Up Time:            0 Days, 8 Hours, 7 Minutes, 19 Seconds

Users of OpenVMS systems can type show system at the command prompt:

$ show system
OpenVMS V7. 3-2 on node JERRY  29-JAN-2008 16:32:04. 67  Uptime  894 22:28:52

Showing the uptime as days then hours:minutes:seconds

Users of UNIX systems (or equivalents) can use the uptime utility to get system information:

$ uptime
01:13:37 up 2287 days,  2:52, 25 users,  load average: 1. 76, 1. 26, 0. 70

See also

• Myth of the nines for a discussion of downtime and availability
• High availability
• Downtime
• Maintenance window
• List of Unix programs
• Reliability disambiguation page

References

External links

• Web sites with longest running systems by average uptime in the last 7 days
• The Uptimes-Project.org
• Tugs Uptime Project
• Uptime Project at The mrEriksson Network Broken since July 2007
• Free Website Uptime Monitoring Service
• Uptime Check
• Free website monitoring, reporting and alerting Service
• uptime(1) – Linux User's Manual
• Windows 9x 49.7 day bug