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Keeping your Home Server running

Keeping it running

Do I need a UPS (Uninterruptible Power Supply) ?

The best way to keep the server running is to ensure that mains power is never lost. For this we have the UPS (Uninterruptible Power Supply). The goal is to keep the server running for the 10 or 15 minutes it takes for you to restore the mains after you trip your house circuit breakers or for the (typical UK) 5 minute power-cut.

You can't expect your UPS to keep the Server running for hours (although if the Server is in sleep mode when the power is lost you will be surprised how long it lasts). Fortunately, if power is lost during sleep mode it is highly unlikely the Server will actually be about to do anything** that could corrupt the data drives, especially if the disks are set to power off before the server goes to sleep.

** well, so long as things like Indexing Service are disabled ...

What sort of UPS do I need ?

Ideally one that will issue a 'warning' to the server that it's batteries are about to expire and the power is about to be removed. The 'Uninterruptible Power Supply' Service (which we disable as a waste of resources on most computers) is then responsible for shutting down the computer.

These days few 'domestic' level UPS come with 'power loss warning' capability, however you may be lucky enough to find a 'Server level' one on eBay, such as many of those in the APC (American Power Conversion) range.

Older 'Server level' (read, 'expensive') UPS issued the 'power loss' warning via a serial link comms port. This is fine, assuming, that is, your servers motherboard is old enough to actually have a serial port :-) ).

The more modern 'Server level' (read, 'really really expensive') UPS come with USB ports.

You can often find a second hand UPS on eBay, sometimes even a 'Server' level unit can be found. Unfortunately UPS batteries have similar life expectancies to those in cars (i.e. run fine for 3-5 years than collapse totally on next use). The cost of replacement is typically prohibitive, since most UPS's use proprietary sized sealed 12v lead/acid batteries. A UPS with dead batteries (i.e. any offered without a guarantee of 'new batteries fitted') can often be found at the same sort of price as a 'spares or repair' computer.

The brave may look into adapting their cheap server level UPS to use an external car battery (not that car batteries are much cheaper).

How to do I ensure the Server will power-up when mains power is restored ?

In the motherboard BIOS, there will be a 'power' setting that allows you to select what to do when mains power is restored. Since (after a power-cut) you want the server to reboot itself automatically, this should be set to 'Always turn on'.

In the BIOS I found a 'Power saving mode' (APM / ACPI) ?

Before Windows 2000, there was no real power saving in Windows so many motherboards implemented their own 'power saving' features in the BIOS. This was known as Advanced Power Management (APM) and allowed Windows NT and w98 computers to 'sleep'. Once Windows 2000 was released with software controlled power modes, the BIOS would clash with Windows and cause all sorts of confusion. If you find 'APM mode' in your BIOS, turn it off.

To work with Windows 2000, motherboards started to offer ACPI (Advanced Configuration and Power Interface). In 2004, this was enhanced to allow Windows to control hard disk power (hopefully your motherboard will be less than 5 years old and will have this feature).

How to I save power ?

You let the Server go to sleep, of course :-)

There are actually 2 basic power saving modes = 'Sleep', when the CPU shuts down but the memory (RAM) contents are maintained, and 'Hibernate', when the whole PC (except the network circuits) shuts down (which means that the RAM contents have to be written onto disk (in the Hiberfil.sys file, which has to be held in the root of the C: drive because it's really just a special type of 'boot' file).

Needless to say, in both cases the main problem is getting the computer to wake up again when it's needed.

How do I make sure Windows will actually 'go to sleep' ?

In 'Start', 'Control Panel', open the 'Display' control. Choose the 'Screen Saver' tab, then click the 'Power' button. In Power Schemes, you will find an option to set times for Turn off monitor, Turn off hard disks and go into System standby ('sleep' mode).

Turn off monitor = set to 'After 5 mins' (even if there is no monitor attached, you might as well save power by letting the graphics display circuits turn off)

Turn off hard disks = set to 'After 25 mins'** (I would expect the server to be used to backup data in 'chunks', for example to hold copies of images saved from your camera's CF/SD card. Once the copy has been made, the hard disks might as well be turned off. When you next send data to the Server, the D: drive will 'wake up'. The C: drive may remain off for weeks (especially if the 'swap file' is moved to D:)

** If there is a power cut, unless you UPS & Server support a 'shut down' warning, it's a VERY GOOD IDEA if the hard disks power down BEFORE the UPS stops supplying mains power ... so if your UPS can be expected to last 30 mins, set the hard disks to turn off after 25.

If you UPS issues a 'shut down' warning, then you want the reverse i.e you want the hard disks to be available whilst the server shuts itself down properly. In that case you should set 'turn off hard disks' to well over the UPS limit.

System standby = set to 'After 3 hours' (it's possible that you might spend some time cataloguing or indexing your photo's etc. before saving them again. So once woken up, the server should 'keep going' for a while 'just in case').

What about 'Hibernation' ?

Unlike 'sleep' mode, in Hibernation mode the entire computer is shut down, with the exception of the network interface (NIC). The NIC circuits will 'monitor' traffic on the Ethernet cable and 'wake up' the rest of the motherboard when it it is 'addressed'. The 'problem' (other than the 'wake up' delay) is that some circuits simply don't wake up at all - and (unfortunately) older motherboards and PCI cards in particular are most likely to suffer from "won't wake up" syndrome.

This, perhaps, is another good reason to use software RAID rather than a plug in PCI controller card.

You will just have to experiment and see for yourself .. generally, the older the motherboard, the less likely it is that Hibernation will work.

If you do enable Hibernation, I suggest you set it to 1 day or more.

OK, that's all about my data backup and file server. Click 'Next >>' in the Navigation Bar (left) for a guide to setting up a Time Server.

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