Uptime

This article is about uninterrupted system availability. For use in logistics, see Downtime. For enterprise computing, see high availability.

Uptime is a measure of the time a machine has been up without any downtime.

Htop adds an exclamation mark when uptime is bigger than 100 days

It is often used as a measure of computer operating system reliability or 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.^{[citation needed]}

Conversely, long uptime may indicate negligence, because some critical updates can require reboots on some platforms.^[1]

Records

In 2005, Novell reported a server with a 6 year uptime.^[2][3]

Netcraft maintains the uptime records for many thousands of web hosting computers.^[4]

Determining system uptime

Microsoft Windows NT

Using systeminfo

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.^[5]

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

Note: Windows Vista Business 64-bit and Windows 7 do not return a "System Up Time" but "System Boot Time" instead.

Using net statistics server/workstation

This method functions properly in versions of Windows released prior to Windows Server 2008 R2 or Windows 7. While the command does run in any current version of Windows, the results are unreliable.^[6] You may, sometimes, replicate this by running the command on a computer followed by using either the WMI query or uptime commands listed here or you can open the task manager and, under the 'Performance' tab, read the uptime value. Note that the reference article only refers to Windows Server 2008 R2, however the issue does exist, intermittently, in other operating systems of the same generation. You may refer to this screenshot for a example of the discrepancy.

C:\> net statistics server | find "since"
Server Statistics for \\COMPUTERNAME
 
Statistics since 8/31/2009 8:52:29 PM

C:\> net statistics workstation | find "since"
Server Statistics for \\COMPUTERNAME
 
Statistics since 8/31/2009 8:52:29 PM

The line that start with "Statistics since ..." provides the time that the server was up from. The command "net stats srv" is shorthand for "net statistics server."^[7]

Using Uptime.exe

Microsoft has also provided a downloadable Uptime.exe utility:

C:\> Uptime
SYSTEMNAME has been up for: 2 day(s), 4 hour(s), 24 minute(s), 47 second(s)

Using WMI

Uptime can also be determined via Windows Management Instrumentation from the command-line with WMIC:

C:\> wmic os get lastbootuptime
LastBootUpTime
20110508161751.822066+060

The timestamp is in the format yyyymmddhhmmss.nnn, so this is a computer that last booted up on 8 May 2011 at 16:17:51.822. WMI can also be used to find the boot time of remote computers as well (Windows permissions allowing), for example with WMIC:

C:\> wmic /node:"my-server" os get lastbootuptime
LastBootUpTime
20101219141712.462006+060

WMI can also be used via a programming language such as VBScript or Powershell^[8][9]

Using Windows Task Manager

Windows 7 Task Manager Performance tab screenshot.

Users of Windows Vista and Windows 7 can see uptime in Windows Task Manager under the tab Performance.

Linux

Using uptime

Users of Linux systems can use the uptime utility (uptime(1) – Linux User Commands Manual) to get the uptime, together with the current time, the number of users and load averages for the past 1, 5 and 15 minute intervals:

$ uptime
  18:17:07 up 68 days,  3:57,  6 users,  load average: 0.16, 0.07, 0.06

Using /proc/uptime

Shows how long the system has been on since it was last restarted:

$ cat /proc/uptime
  350735.47 234388.90

The first number is the total number of seconds the system has been up. The second number is how much of that time the machine has spent idle, in seconds.^[10] On multi core systems (and some linux versions) the second number is the sum of the idle time accumulated by each CPU.^[11]

BSD

Using uptime

Like Linux, BSD based operating systems such as FreeBSD and Mac OS X also have the uptime command (See uptime(1) – FreeBSD General Commands Manual).

Using sysctl

There is also a method of using sysctl to call the system's last boot time^[12]:

$ sysctl kern.boottime
kern.boottime: { sec = 1271934886, usec = 667779 } Thu Apr 22 12:14:46 2010

OpenVMS

Users of OpenVMS systems can type show system at the command prompt.^[13]

$ show system/noprocess
OpenVMS V7.3-2 on node JACK 29-JAN-2008 16:32:04.67  Uptime  894 22:28:52

This shows the uptime as days then hours:minutes:seconds.

External Uptime Measuring

There are a many external services which can be used to monitor the uptime and downtime as well as availability of a service or a host. Some examples:

• Pingdom
• WatchMouse^[14][15]

See also

• List of Unix programs
• Maintenance window
• System profiler‎
• Website monitoring
• Uptime, the first half of a double album by the Kleptones

References

1. ^ How to install Windows Updates with only one reboot
2. ^ Marathon servers: Novell shows off servers with longest uptime
3. ^ Uptime Workhorses: Still Crazy after all these Years
4. ^ Netcraft: Sites with longest running systems by average uptime in the last 7 days
5. ^ Tracking down uptime in Windows XP
6. ^ "Net statistics server" output displays incorrect time
7. ^ How to find Windows uptime?
8. ^ How Can I Tell if a Server has Rebooted?
9. ^ How Can I Determine the Uptime for a Server?
10. ^ Reference Guide For Red Hat Enterprise Linux 4.5 - 5.2.30. /proc/uptime
11. ^ See comments to the patch
12. ^ sysctl(8) Mac OS X Manual Page
13. ^ PARSEC Group - Undocumented OpenVMS Features
14. ^ Robin Wauters (19 January 2010). "WatchMouse Monitors 26 Popular APIs So You Don't Have To". Techcrunch. http://techcrunch.com/2010/01/19/watchmouse-api-status/. Retrieved 21 April 2011. 
15. ^ Wikimediafoundation.org