2A/3A fuse to discriminate with 16A b-curve MCB?

[ban-all-sheds]

We've looked at blades but not really considered them much at this stage. They don't help when a customer needs to plug in kit that they already own themselves and just want power and connectivity, though, as opposed to leasing the kit from us (in which case we could sell them a blade, or a virtualised server, etc). But I agree, that's another matter

Ah.

When I read your original post I thought you were the customer renting space in a datacentre, not a supplier renting it to customers.

Hope you weren't too upset by my MM comment...

 

[holmslaw]

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[ban-all-sheds]

BAS, you're out of your depth and talking bollerx.

Really?

If you say so, but it's strange how I've managed to earn my living doing things which require me to know about what I've said here, and get it right, for many years, isn't it......

You might be a part P expert but that is the extent of your electrical knowledge.

Dream on.

 

[holmslaw]

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[ban-all-sheds]

As I've told you many times in the past, you would not be tolerated in any professional situation because you are a too pedantic and assertive.

If you say so.

My CV says otherwise, but I'm sure that as you have never met me, and have no idea what jobs I've done, you must be right.

And as soon as your audience realises that you are ignored.

Do they ignore me before asking me relevant questions, thanking me for the answers, and thanking my employer for my contributions, or afterwards?

I can't tell, but I'm sure that as you have never met me, and have no idea what jobs I've done, you must know.

And you have never argued against that assertion because you have no argument.

I've probably never argued against it because it is so ludicrous.

Stick to making pronouncements about part P, which you are very good at, the pronouncements I mean, the content is probably bollerx.

Dream on.

 

[very_pointy_ears]

We've looked at blades but not really considered them much at this stage. They don't help when a customer needs to plug in kit that they already own themselves and just want power and connectivity, though, as opposed to leasing the kit from us (in which case we could sell them a blade, or a virtualised server, etc). But I agree, that's another matter

Ah.

When I read your original post I thought you were the customer renting space in a datacentre, not a supplier renting it to customers.

Hope you weren't too upset by my MM comment...

Hi, not at all. It's not our data centre nor was it our decision to have the sort of power supply they've given us. We're just a customer of the data centre, and have our own customers who want to co-locate stuff in the racks we rent, as well as us using the racks for our own kit. In effect we're re-selling the rack space and power in smaller chunks, along with some 'net connectivity that we get through various tier 1 carriers and peering agreements.

Most customers just want to plug one or two servers in and as such need just a few U, whereas if they went direct to the data centre they'd have to buy a whole rack.

It doesn't stop them getting upset when their kit goes offline, though, which on several occasions has been caused by someone else's PSU going bang and tripping the breaker to the entire rack.

Some of our kit does have dual PSUs but much stuff does not, unfortunately.

I hope that clears up the confusion

 

[electronicsuk]

At the rack level you would not have duplicate feeds, and none of the kit would be fed from different phases, they could be fed from different sources but not different phases.

Yes you would and yes you do and yes they can be and yes they are.

BAS, this aint part p, this is real world , why not provide evidence for your stupid assertions

Sorry chaps, but I'm with BAS on this one, and as I jointly run a hosting company and am currently doing some consultancy work for power at a datacentre buildout, I feel well placed for making these comments.

While cheaper datacenters do not install redundant power to rack level unless specifically requested, high-end DC's will provide dual redundant feeds at the rack, often each from their own UPS. Dependant on the level of redundancy, there may be multiple backup generators and also diverse feeds from the grid.

Whether or not you would consider the feeds at rack level to be on different phases is a matter of opinion, as large UPSs are often supplied in TP and then output in SP, but each redudant feed may be supplied via a different UPS and distribution path.

 

[ban-all-sheds]

BAS, this aint part p, this is real world , why not provide evidence for your stupid assertions

http://communities.vmware.com/thread/177952

Please let me know if you have any more stupid assertions you would like me to address.

 

[holmslaw]

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[ban-all-sheds]

Ok some servers come with built in dual supplies, but you would still be a fool to connect them to different phases. Because a failure of one phase on a 3 phase breaker will cause the breaker to trip. Thats why you use different sources for the power supplies.

1) The different phases may be presented to the rack as 3 single phase circuits from 3 single phase breakers in a DB, so one of those could trip in isolation.

2) Some manufacturers document connecting supplies to different phases as best practice for resilience.

 

[holmslaw]

..

 

[davelx]

We have several very large datacentres (pics of one below). We use dual power supplies fed from two different circuits, coming via two different building risers from different substations - we have two in the basement - fed from different suppliers, with the incomers following diverse routes and entering at different ends of the building. Plus a roof full of aircon and generators that can run the lot if both supplies fail.

Each rack has A & B power distribution strips fed in this way - and of course the fan trays have to have dual power too.

So yes, serious datacentres DO have dual feeds to the racks as BAS says, but they tend to feed these from entirely separate supplies, as Holmslaw says.

Lesser datacentres probably do all sorts of variations on a theme.

(And even then we had a cascade failure a couple of years ago - it was in the news)

 

[holmslaw]

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[ban-all-sheds]

I'm sure I recognise it....

 

[holmslaw]

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