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Client asks for 100% uptime

serverfault.com

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Re: Client asks for 100% uptime

#31

Post by oconnore »

brown9-2 wrote: post #28
oconnore wrote: post #26

I don't understand what the issue is. The client wants you to plan for disaster, and they aren't math oriented, so asking for 100% probability sounds reasonable. The engineer, as engineers are prone to do, remembered his first day of prob&stat 101, without considering that the client might not. When they say this, they aren't thinking about nuclear winter, they are thinking about Fred dumping his coffee on the office…

But "three 9 reliability" is still not the same thing as 100%. The contractor has a right to be concerned about the 100% figure making it's way into a contract.

No, three 9 reliability for a single server.

1-.001^3 = .999999999, which is under a second expected per year, which the client will never notice even with good monitoring tools, and therefore will never invoke the contract.

Re: Client asks for 100% uptime

#32

Post by blrgeek »

Looks like client is asking for off-site failover, not really 100% uptime and the OP doesn't know how to achieve it over a WAN. Esp if this is a real enterprise customer, they want Disaster Recovery (DR).

This is a solved problem, albeit not a commonly known solution. Any of F5, Radware, and other expensive boxes can do this. This can also be done through DNS or with HA-Proxy etc.

Re: Client asks for 100% uptime

#33

Post by dmbaggett »

Look at it from a business, rather than engineering perspective. Forget the achievability of the 100% target for a moment -- what target can you realistically achieve? Then, what does the contract say the remedy is for breach? As long as the remedy is not huge and -- this is very important -- is clearly quantifiable, it may be just fine to enter into such an agreement.

You need the remedy to be clearly quantifiable (X dollars per Y minutes, for example) because otherwise you create an opportunity for dispute when the inevitable occurs and you breach. Resolving such a dispute could very well cost more than the remedy itself, even in the worst case.

From an ethical standpoint, I would only enter into such an agreement with an understanding that "while we agree that it makes sense for you to request that target, we think realistically that we'll be closer to 99.9% (or whatever you truly believe)". Entering into an agreement with a 100% uptime clause is different from setting an expectation that uptime will actually be 100%.

Re: Client asks for 100% uptime

#35

Post by illumin8 »

marquis wrote: post #23
illumin8 wrote: post #21

Look at F5 networks Global Traffic Manager. It's really just a fancy DNS server. You set your TTL (time to live) down to just a few seconds and it monitors your main and standby sites. If one of the sites goes down it changes your A records to point to the new site. It can even do load balancing across sites based on response time or number of connections. They are expensive, but this is how large companies like Yaho…

This is the kind of service I'd love to attack as a side project, it's fascinating. Though I'm sure someone out there reading this, has something like this service but affordable for startups?

There is a lot of room in this market for competition from open source projects. Really, the concept is so simple that it could be done with a shell script for simple failover:

(pseudo code) if (curl http://ip of main site) fails then copy alternate zone file to bind dir service named reload fi

You get the idea... F5 Networks is really just a fancy DNS server running on a BSD based OS on an x86 appliance. Zeus, which another commentor mentioned, has an AWS version and will let you run it on your own hardware if you like.

I'd love to see some open source competition for this space, or even low price competition.

Re: Client asks for 100% uptime

#36

Post by lutorm »

_corbett wrote: post #14

I was at an Akamai presentation the other day in which the salesperson claimed "100% reliability" of their services "not 99%, not 99.9% but 100%".

Was it a promise of future reliability or a statement about historical reliability over some time frame? Because everything has been working 100% reliably until it fails...

Re: Client asks for 100% uptime

#39

Post by moe »

_corbett wrote: post #14

I was at an Akamai presentation the other day in which the salesperson claimed "100% reliability" of their services "not 99%, not 99.9% but 100%".

These claims are common for all the big CDNs and ISPs but it's always accompanied by half a page of fineprint that rids them of any liability when an outage happens and limits compensation to a microscopic penalty (usually a fraction of the monthly fee).

You can negotiate steeper penalties with funky multiplicators - but they make you pay through the nose for such an arrangement (for obvious reasons).

Re: Client asks for 100% uptime

#40

Post by SoftwareMaven »

oconnore wrote: post #26

I don't understand what the issue is. The client wants you to plan for disaster, and they aren't math oriented, so asking for 100% probability sounds reasonable. The engineer, as engineers are prone to do, remembered his first day of prob&stat 101, without considering that the client might not. When they say this, they aren't thinking about nuclear winter, they are thinking about Fred dumping his coffee on the office…

This is the answer missing from SF. This is the true "what would it take" that could be presented back to the client.

Would the client go for the cost? Who knows,but that's the client's decision.

Add a little more data on the DNS failover and it would be a good community wiki entry there.

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