Jump to content

What to do about a power cut?

browolf

By browolf
in Wired Networks

 Share

What's best  

34 members have voted

  1. 1. What's best

    • Leave everything off for 2 weeks
      29
    • Off then on then off then on
      3
    • something else / don't know
      2

Recommended Posts

browolf

browolf

Posted
Posted (edited)

So we're having two buildings demolished in the summer holidays and part of the work involves switching the whole school power over to a generator for at least a week.

 

We all agree that we should unplug everything (every plug in the whole school) to protect them from a power spike when switching on the generator but we don't agree on whether we should turn critical things back on after the switch over or just leave them off until normal power is resumed.

 

IT infrastructure is:

 

1 yr old servers (70%)

7 yr old servers (30%)

 

1 yr old switches (20%)

20 yr old switches. (80%)

 

The great unplugging will be on a tuesday morning and the generator will be connected and turned on wednesday. I was going to come in on wednesday or thursday and turn back on the servers and switches. Then on the week after turn them all off for the generator removal and then turn them on again when the normal power is turned back on.

 

My colleague says turning them off then on then off then on a week later is more risky than just leaving them off for a week.

 

I'm worried the old stuff will definitely be broken after a week off but might not be broken from being off and then on twice.

 

What's best?

 

edit: nothing is required to be on during this time.

Edited by browolf
crc-ict

crc-ict

Posted
Posted (edited)

I'd be asking questions about the 'quality' of the power coming in from the generators before I brought things up running off it as not all generators are created equal.

 

Although one would hope that something of a suitable size to power a whole site would be providing grid quality power anyway.

 

As far as I thought, the risks in powering off things like switches and servers was due to the cooling down and then heating up effects, which wouldn't be different between leaving it off for a day vs leaving it off for 2 weeks (assuming proper storage conditions etc etc). Obviously putting it all back on during the generator period means that you will go through two cooling/heating cycles rather than one (albeit longer one) if you leave them off for the 2 weeks.

Edited by crc-ict
elsiegee40

elsiegee40

Posted
Posted (edited)
Also the Generator might only be on during the day due to Noise pollution issues.

 

 

 

My colleague says turning them off then on then off then on a week later is more risky than just leaving them off for a week.

.

 

[emoji782] Time has nothing to do with it. Although anything with a dodgy mobo battery might have problems with a longer outage.

 

Turn them off and leave them off until it’s safe.

 

The only thing I would consider is the UPS batteries. Keeping them fully charged (without anything plugged into them) might be worthwhile.

Edited by elsiegee40
6Foot2

6Foot2

Posted
Posted
Also the Generator might only be on during the day due to Noise pollution issues.

When we had to upgrade our intake we had on-site generators to keep things alive during the work. As you say this was not popular with the neighbours, and it generated (no 'pun' intended) many complaints. We decided to keep the power on because although the work was going on during a holiday, there were several lets on over the same period, and the groups hiring the school could not be without power.

PotNoodleTech

PotNoodleTech

Posted
Posted (edited)
Nothing will be needed

 

If nothing is needed then leave it all unplugged for the duration of the works.

 

Ask yourself this, if you keep it all on, can you afford to replace the 80% switches and 30% servers that are likely to fail due to bad power conditioning due to old bulged capacitors etc if the generator has just one hickup?

 

Risky.

 

The other thing is - what make and model generator(s) are they planning using to keep the school running? I'd expect the generators needed to run a secondary school to actually arrive on the back of a large lorry. If the boys turn up in a pickup truck with a hand held 3kw one from machine mart then your plans to keep everything on are in severe trouble.

Edited by PotNoodleTech
6Foot2

6Foot2

Posted
Posted
...The other thing is - what make and model generator(s) are they planning using to keep the school running? I'd expect the generators needed to run a secondary school to actually arrive on the back of a large lorry. If the boys turn up in a pickup truck with a hand held 3kw one from machine mart then your plans to keep everything on are in severe trouble.

Can't remember the make/model of 'our' generator (while not an exact match for size, it conveys the idea)

 

Generator.jpg

3s-gtech

3s-gtech

Posted
Posted
Decent UPSs should be smoothing your input already, and should deal with any dirty power coming from generators (as long as they're decent, pure-sine ones). The risk of the genny running out of fuel over a weekend, being switched off for some reason, being nicked (it happens) would suggest taht off would be safer, but bear in mind that older servers, after being off for that amount of time, may not come back up without new PSUs.
andyfield

andyfield

Posted
Posted
Last year we had power issues and had to run the entire school from a generator whilst the school was still open. Everything worked fine without any issues. Wise to think about spikes when things are changed over as we did the same, however everything ran fine on the generator. The only issue we had for a couple of days was a result of them wiring the phases wrong which meant all the drills in DT went backwards!
  • Thanks 1
PotNoodleTech

PotNoodleTech

Posted
Posted
Can't remember the make/model of 'our' generator (while not an exact match for size, it conveys the idea)

 

[ATTACH=CONFIG]54187[/ATTACH]

 

That looks like an approx 30KW generator with extended run time fuel tank.

 

30KW doesn't actually go very far when you start adding up how much your servers and all switches and other POE equipment uses. That's not even considering any lighting or heating, or if just one person plugs a kettle in.

 

I guess the real question is is the generator going to run the entire school, or just all the IT equipment? IF it is just IT, how are you going to stop people plugging things in and turning them on?

browolf

browolf

Posted
  • Author
Posted
That looks like an approx 30KW generator with extended run time fuel tank.

 

30KW doesn't actually go very far when you start adding up how much your servers and all switches and other POE equipment uses. That's not even considering any lighting or heating, or if just one person plugs a kettle in.

 

I guess the real question is is the generator going to run the entire school, or just all the IT equipment? IF it is just IT, how are you going to stop people plugging things in and turning them on?

 

I think the generator was mainly for the alarm system and cctv, and then the servers. But since the prevailing opinion is leave them off, no longer the servers etc. I think no staff will be allowed in.

  • Thanks 2
elsiegee40

elsiegee40

Posted
Posted
You may find a few fans in switches etc. either seize or screech when turned back on from cold!

 

So true! Our sounded awful after a one week shutdown. They quickly settled down though

  • Thanks 1
QwertyMash

QwertyMash

Posted
Posted
I personally would only be turning on mission critical services, as in ones that 2 weeks of downtime would be too costly. If the gear could afford to be off the entire time I would leave it off.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


×
×
  • Create New...