Question: I wounder how important it is to have an UPS for a server. Everyone seems to use UPS for servers but not for client computers.

In example, if I use Windows Small Business Server on a small network for Active Directory and storing the users home directory for backup is it still useful with an UPS, why? If a power outage happens, shouldn't the filesystem handle that, so no files are corrupted? And in this case I think the problem is the same on the clients.

I do understand that it can be useful on servers when changing the server configuration, but that is done during a very limited time and it sounds like it's more worth to do good backups before the configuration.

And when thinking about database transactions, I think that the transaction logic in the database management system should handle it, that's what transactions are for.

And finally, if an UPS is used, doesn't the server applications need to have support for it? outherwise the power outage is only delayed? Or is it only the operating system that needs the UPS?

### Why is an UPS needed for a server but not for clients?

Answer: 
Accidents do still happen. RAID cache batteries not working properly is a concrete example, but journaling filesystems and transactional integrity simply aren't guaranteed when the power is pulled.

Plus, any UPS worth a damn also does line conditioning to protect the hardware from current and voltage variations, extending the lifetime of your hardware.

Why servers and not desktops? Some places do, but it's expensive. How much is the data on any client worth? How much is the data on the server worth?
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> And finally, if an UPS is used, doesn't the server applications need to have support for it? outherwise the power outage is only delayed? Or is it only the operating system that needs the UPS?
>  Why is an UPS needed for a server but not for clients?
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> 
> 

Who says that clients don't need a UPS? All systems in our environment are protected by a UPS - from every server to each desktop.

You are correct that a UPS only delays the power outage. However when a power loss occurs the UPS communicates to the OS through a USB cable (most common nowadays). This allows the UPS to notify the OS when the battery is about be empty and the OS can begin **gracefull** system shutdown. This is something that is not possible in a normal power outage without a UPS. ***The power company will not call you and tell you that a tree is going to fall in 10 minutes and kill your power.***

Your assumptions about how a computer handles a loss of power are not realistic. Most of the time there might not be any harm, but there is no need to gamble. One problem on a production server and you will rue the day that you decieded you did not need a UPS.