There is a server that is used from 4:30 am in the morning until ~ 22:00.
Should it be turned off? I think that it is a server and that it won't have a problem to stay on, but serious professors are telling me that it is dangerous and that HD can fail within 2 years. The server owner believes that his old server running from 1995 without backup and a single hard disk (if the hard disk fails he is screwed) had no problem because he used to turn it off at nights.
What do you believe for this?
Now it has a RAID 1 array, external hard disk backup, and serveral full hard disk backups on DVD and over the internet.
To liken it to a car analogy: A taxi can do over 500,000 kilometers before it needs an engine rebuild. The reason for this is because they are always running, 24/7, and after a car's engine is up to temperature, the amount of wear it receives while it is running is greatly reduced.
A computer is kinda the same. The majority of the "wear" on parts can happen when the server is booting up. Just attach an amp meter to your computer, and turn it on. When it starts up, the power it draws climbs very high, and then it settles down once all the disks have spun up and the processor is initalised. Also, think about how much disk activity the server undergoes during boot up vs when it's working. Chances are the disk access from booting the OS is fairly solid activity, whereas when the OS is running, unless it's a very heavy database server (I'm guessing not), the disks will most likely stay fairly idle. If there's any time it's going to fail, chances are it will be on boot up.
Turning your server on and off is a stupid idea. Not only to mention most servers can take upwards of 2-5 minutes to just get past the BIOS checks, it's a huge amount of wasted time too.
2018 Update: Given that most computers are now essentailly entirely solid-state, this answer may no longer be as accurate as it once was. The taxi analogy doesn't really suit todays modern servers. That said, typically you still generall don't turn servers off.
Turning the server off and on everyday would likely cause it to fail faster than leaving it on.
The only thing I can see that's even close to right about what you've been told is that drives can fail within 2 years. They can in fact fail at any time. I'm sure most of us have received at least one brand new drive that was DOA. On average server drives will last anything from about 3 years upwards, with 10 or 20 years not being too uncommon. That doesn't mean any individual drive won't fail a whole lot sooner.
Servers (meaning a machine with proper server grade components) are design to run continuously. There is no reason to shut it down at night but some very good reasons to leave it running. Nighttime, or whatever other time is "quiet" for a given system is the time to run all the maintenance and automation.
e.g. Backups are best taken when there is no or little user activity. This helps to ensures backups are consistent. Sure there are ways around this but why not give your backups every chance of success when there is nothing to lose by doing so?
Someone running a "server" with a single disk and no backup is a fool, not an admin. The only reason he got away with it is sheer dumb luck. It had absolutely nothing to do with shutting the machine down at night.
Servers are meant to operate 24x7. Shutting servers down overnight is extremely non-typical. Server hard drives are designed to be more reliable than desktop drives and now that you have backups and RAID 1, you will not suffer data loss if one of your two drives fails.
What i would worry about now for this 16 years old server is a motherboard or non-redundant power supply failure.
I've never turned a server off at night before.
Hard drives will fail when they are going to fail. Turning the machine on and off isn't going to make the drive fail slower. I've seen hard drives shipped from the vendor that were already bad, and I've seen disks running (and actively being used) for 5+ years without failing.
Your professors are idiots.
This also puts a bigger "human aspect" on the server. Even if you use power settings to turn it off and on at the correct times, you should have someone monitor the server to make sure all required services, etc. start up properly.
That's precious time you can be teaching the professors about backups and RAID.When do you run backups? I would give anything for a 6-hour window to run my daily backups, updates, hotfixes, etc. If nothing else, this downtime can be used for that.
I challenge you to go to these "serious professors" and provide research showing that leaving the computer on 24x7 is bad for it. I'd like to back up what they are saying.
Realistically most servers are expected to be available 24/7. Plain and simple.
On the off chance yours is not, there is very much a debate between which will cause more wear on your server, the constant expanding and contracting between turning your server on and having it heat up, and then turning off, and having it cool down, or the wear on components from constant use.
I have yet to see any research on which is worse, and I'm very much doubting your professor's have access to some research claiming differently.
In the end you'll have to make the decision based on your needs, but the cost benefit to most business's is to have their servers and services available all the time, not just when someone gets in and turns it on. Especially when there is a debate that you may in fact be making more trouble for your servers by turning them off.
What is more important is the cooling. Cooling makes a big difference. The temperature inside the box may much higher than the room. I would install software to monitor that like everest. Comparing the modern hard disk's to the one you replaced, they run hot. Some need fans to cool them Sometimes a small fan can make a big difference. The life of the HD and server will depend on the cooling.
Yeah not an option. Tell your professors that industry standard is to leave them running 24/7 and to have a warranty for failed hardware. If the server is 16 years old I imagine you're not going to get that warranty.
If the server did explode, what recovery time would you have to build a new one with the backed up information? I'd start hinting to the clients that their server has reached end-of-life and they should start looking for funds for a new one.
It's true that the mechanical stresses of power cycling is hard on the HDD. Also, there were some older drives that (when cooled down enough) could stop working altogether because of "stiction".
With inadequately designed circuits, inrush currents from turning the machine on could also stress some components, though this is not all that likely.
That said, there is some truth that leaving the machine on takes its toll: capacitors. The numerous electrolytic capacitors on the motherboard is likely to be the weakest link of system reliability. These capacitors are rated for their current/voltage handling capability, operating temperature and lifetime. Typical capacitors will be rated for several thousand hours. Heavy-duty/long-life caps are rated for several tens of thousands of hours and higher temperatures.
This is why you sometimes see motherboards for sale featuring "server grade capacitors" -- because those machines operate at full speed 24x7 and chew through their motherboard lifetime.