Time Machine Frequently Asked Questions

What's the most efficient way to make Terminal Services clients see their local time instead of the server's time?

How does Time Machine support roaming users that can connect to a Terminal Server from different time zones over a short period of time?

Will other users on the same system see "my" virtual date and time and get confused?

Why use Time Machine and not just reset the system clock?

Will Time Machine cause file timestamps to be updated to the virtual date and time? I am worried about my backups and system logging.

Can I have different programs see different virtual dates and times on the same system?

I am worried about my backups and system logging. Will TM cause file timestamps to be updated to the virtual date and time?

My session and job can create child processes. Will the child processes also see the virtual date and time set by their parent process?

My batch job streams another job within it. Will the nested job also see the virtual date and time set by the top-level job?

Other than Year 2000 testing, what else can I use Time Machine for?

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What's the most efficient way to make Terminal Services clients see their local time instead of the server's time?
You can set up one group of users per time zone, and put those groups on Time Machine. Each group can be given a time offset from the server's time, and can be automatically loaded by Time Machine during system initialization. Changes to group membership in the OS account database are automatically reflected into Time Machine and take effect the next time the affected users log on. Groups, as well users, can be added to or removed from Time Machine through flexible and comprehensive utilities without affecting the other groups and users being served by Time Machine. Those changes are effective immediately.

How does Time Machine support roaming users that can connect to a Terminal Server from different time zones over a short period of time?
Roaming users that cannot get the correct local time through time-zone-based group membership because of their frequent time zone crossing can create their own virtual clock by using the command "tmuser -a -h [-m ]" after logging on. Their new virtual clock will override the group virtual clock they would normally use. In order to allow users to set their own clock, the utility tmuser_setup must have been run by an administrator. This virtual clock will last until a system reboot or it is manually removed by the user or an administrator.

Will other users on the same system see "my" virtual date and time and get confused?
No. Only the processes (and their descendant children) belonging to a user under Time Machine will see the virtual date and time set for that particular user.

Why use Time Machine and not just reset the system clock?
Productivity is boosted since you are not limited to one clock. Time Machine also avoids single threaded testing, time-bombed programs and expired accounts! Re-setting the hardware clock forward will affect ALL programs trying to see the system's clock, including the password program and software with expiration dates. Time Machine allows users to see a virtual time while keeping the system clock to the present time. Time Machine addresses time-bombed programs with its exclusion list. Any programs listed on the exclusion list will not see the virtual clock but rather will continue see the system date and time.

Will Time Machine cause file timestamps to be updated to the virtual date and time? I am worried about my backups and system logging.
Unlike resetting the system clock, Time Machine is safe and transparent to the file system. The file system still sees the current date and time and will update the file timestamps accordingly by default.

Can I have different programs see different virtual dates and times on the same system?
Absolutely. For example, a clock can be setup for each user so that they see their respective time zone.

My session and job can create child processes. Will the child processes also see the virtual date and time set by their parent process?
Yes. The scope of the virtual date and time is visible to the process that activates Time Machine and all its descendant children processes.

My batch job streams another job within it. Will the nested job also see the virtual date and time set by the top-level job?
The nested job is NOT a child process of the top-level job, so by default it will not be affected by the virtual date and time. However, if virtual date and time is desired, you can: a) set a flag to cause the job to "inherit" it from the streaming job or session, b) use the Logon Automation feature, or c) simply insert a Time Machine call in the nested job.

Other than Year 2000 testing, what else can I use Time Machine for?
Time Machine can be used for training. For example, you can use Time Machine to simulate the exact environment for month-end or quarter-end processing. It can be used to redo certain date and time-sensitive operations. Let's say you missed quarter-end processing due to a hardware problem. Now, three days later, you can use Time Machine to regenerate the quarter-end report as if it were running on that exact date and time. Users in Japan can generate reports in their local time with Time Machine on a system located in the United States. The possibilities are endless. View Time Machine Case Studies to learn how current Time Machine customers are using Time Machine.

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Michael Morrison - Storage Management and Date & Time Testing