Thread: redundancy

PSUs - both would be drawing power, you're also taking up infrastructure that can be used to make money elsewhere, so it will cost you more.

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Depends how redundant you want it.

Are you talking about a server with 2 PSUs connected to the same PDU in the rack, or a server with 2 PSUs connected to separate PDU's within the rack and maybe even coming off a separate power feed into the rack?

If the latter, it will get complex and the provider will not offer such a service for no extra cost.

We have customers using servers with 2 PSUs, in the event one fails. They are also connected to a different PDU where possible. But ultimately the power bars feed off the main PDU connected to the big socket provided by the DC under the floor.

Network connections are some what easier to do. You can have multiple switches in one rack, one network connection into each switch. But this will be affected by the single power feed into the rack if the main power goes to that rack / suite / floor / building. You could have a cable laid into the rack terminating at another switch in a separate rack / suite / floor / building as the secondary interface. But if the power does go in the rack, the server will turn off, your redundant network connection won’t help there - Unless of course PoE gets juiced up.

Unless you’re in RedBus (Awaits a backlash), you’ll have more chance of a switch PSU failing than power to the entire rack.

Two PSUs = roughly twice the power draw in our experience. If you use good quality PSUs, from the likes of Zippy etc. you're not all that likely to loose a PSU within it's useful lifetime.

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Originally Posted by JGraham

James[UH] - do you charge those customers extra for using two power connections?

We base it on how big the co-lo order is. I.e. how much space are they taking and bandwidth. I wouldn’t give them an additional power socket for free if they only have one machine. Increase that to 2+ high spec machines with your own switch / firewall and we and I'm sure many others (Although the term "big" respect of a co-lo order will vary greatly between providers) will do something similar depending on the size of the order and length of the contract.

If a clients server has two power supplies we always connect both up and don't charge extra for it.

We've just started using static bypass controllers in our racks for a new 'venture', and these work well. The switch takes feeds from A and B power supplies which are diversely routed to the rack from different UPS and national grid feeds. Then if the power to that UPS (or the UPS) fails, the switch flicks over to the alternate supply with no loss in power.

This allows us to connect dual power supply servers to diverse feeds at no extra cost (as it's provided as standard by the DC to us).

Which DC Matt.... GS?

Originally Posted by Maff

We've just started using static bypass controllers in our racks for a new 'venture', and these work well. The switch takes feeds from A and B power supplies which are diversely routed to the rack from different UPS and national grid feeds. Then if the power to that UPS (or the UPS) fails, the switch flicks over to the alternate supply with no loss in power.

And if the switch its self fails?

In Dataplex Budapest.

The switches are internally redundant, supplied by MGE UPS Systems. They also have RS232 outputs so you can find when then power to a certain feed tripped, and other data.

Maff - You got MSN/ICQ etc.? Wouldn't mind a quick word about them (We actually get A + B feeds) and a couple of other bits.

Cheers,

[QUOTEJ
After investing in redundant solutions (power supply/nic specifically) do providers generally support this?
[/QUOTE]
Some of us yes.

For example, at little or no cost could my server have a second power connection, and two network ports? Of course, in theory no extra resources would be used, as the redundant solutions would only be used when required.

Not sure why you think it shoudl be little or no cost
2 psu's will take up two power outlets
draw more power than a single psu
to be done correctly as per other posts, 2nd psu should connect to separate kit, on separate phases of ups/building power etc, which all costs money.

2 network ports which not using twice the transit, use two ports on the switch, etc, and unless done with some form of teaming with nat, cannot both be active on teh same ip ready for failover anyhow.

Yes psu's fail, *sometimes* having a redundant psu helps (althouhg we've seen the boxes still end up rebooting themselves) - other times the psu going also takes out the motherboard - so you're still dead.

similarly hard-drives fail, cpu's fail, fans fail, onboard nics fail ... essentially every component can and eventually will go wrong. buying better kit in the first instance can limit that, although i've know cheap case/psu combinations run for 5 years - its all to do with environment, cooling, quality/manufacturer and luck.

JGraham:I agree it may draw more power, but that shouldnt be a problem as long as its within the limits of the contract

JGraham:This would cost the provider nothing. Additional ports I understand may be an issue. However, if there are spare ports then why not

JGraham:looks like i'm going to have to wait till I can afford my own rack to implement my own redundancy systems.

I never disagreed with the need or application of redundancy - we have plenty of colo clients with multiple psu's connected to separate APC's on separate phases, multiple nics connected to multiple switches in separate vlans etc etc

The "question" I had was merely why you though it shouldnt cost extra for the additional power, the additional power port, the additional phase run to the rack, the additional apc, the additional switch, the extra setup etc.

Its the different view between consumer and service provider - you view them as "spare" switchports which cost nothing - we see a 3 grand switch with maintenance of 1k with 24 ports and give each of them a "cost" off £125+£42 ~ equating to appx £15/month - if you want an extra one fine, depending on the service you're taking we may/may not want to charge you for it.

because it's not currently utilised doesnt make business sense to give it away free - especially as it then means you dont have it to sell. I personally feel you should charge people for what they use rather than charging them all more because some might use extras.

Plenty of providers will offer you the additional features you need to improve redundancy, you dont need you own rack for it, but if you're heading that route - ideally you need two racks in case 1 falls over