Hosting companies say that my site will be up 99.99% of the time. Meaning that it may be down for at most 5 minutes in a year or some crazy figure like that. How do they guarantee this? Mirroring? Load balancing? Or is it just some claim that is hype and no substance? Moreover, how do I monitor this from a customer's perspective?

Thanks,

Hopper

a lot of times i will see they say up 99.9% of the time but they only guarantee an amount around 94% up to 99.4% depending on how good they are.

99.9% = 43.2m Down Time , so 99.99% is even less than 43 minutes downtime per month.

Some high end hosts get insurance so that if they are down their insurance pays the refund or whatever the SLA says.

A fantastic book that i can recommend that covers uptime and a lot more is "Strategies for Web Hosting and Managed Services"
by Doug Kaye(http://www.amazon.com/exec/obidos/ASIN/0471085782/qid=1026433659/sr=8-1/ref=sr_8_1/103-6360585-2701434).

Read it once and will be reading it again.

Watch out for the disclaimers!
Some hosts will offer a 99.xx% uptime guarantee, but they say the downtime only starts when you report it to them. Or they'll have so many restrictions that it turns out to be of no substance.

you can monitor any web site using companies like internetseer.com and the like!

Just a small comment...

I have often found web sites like internetseer.com to be inaccurate at times. I have monitored a few sites with them and received a report saying the site was down but in reality it was running fine:D

Originally posted by David@Digisurge
Just a small comment...

I have often found web sites like internetseer.com to be inaccurate at times. I have monitored a few sites with them and received a report saying the site was down but in reality it was running fine:D I've never had that problem with Internet Seer.

I read an interesting article about how anything above (true) 99.7% is really not possible in many situations and not really feasible and that 99.7 is really "good enough" and that trying to meet an uptime you can't will usually end up in an uptime less than you COULD meet if your expectations were in line.

Originally posted by iamdave
I've never had that problem with Internet Seer. No.. only people affiliated with webhosts do. It's a conspiracy. They're all in on it together. :eek3:

Originally posted by David@Digisurge
Just a small comment...

I have often found web sites like internetseer.com to be inaccurate at times. I have monitored a few sites with them and received a report saying the site was down but in reality it was running fine:D

I agree - InternetSeer does produce phantom outages. I would recommend not putting all your (monitoring) eggs in one basket. Use another monitoring system also as InternetSeer do report outages that do not exist.

Originally posted by Dixiesys
I read an interesting article about how anything above (true) 99.7% is really not possible in many situations and not really feasible and that 99.7 is really "good enough" and that trying to meet an uptime you can't will usually end up in an uptime less than you COULD meet if your expectations were in line.

Where did you read that Dixiesys? It certainly is possible to get 100%, can be a bit of a tall order of you are looking for 100% over a year but certainly not impossible.

Originally posted by Dixiesys
I read an interesting article about how anything above (true) 99.7% is really not possible

I'd like to read that article, because it sounds like bull to me. 99.7% uptime means more than TWO HOURS offline a month. Based on the reports from my connection monitoring software, one of my colo's has provided 100% uptime for at least the past 3 months.

In my opinion this whole area is meaningless hooey!

There's a whole list of stuff that is likely not to be covered by any uptime guarantee (eg problems within a bandwidth provider's network or between their network and someone else's, malicious activity like DOS attacks or server hacks, downtime that you don't detect and report, earthquakes, floods, terrorism, the FBI breaking the doors down and confiscating the gear...).

Even if someone says "we guarantee 100% uptime" and the caveats on that "uptime" are ones you can accept, does it mean your website will be up 100% of the time? No sir, it means that if it isn't, and if you can prove it hasn't been to the provider's satisfaction (could be very difficult if they want to argue about it), then they will give you some money back. Maybe.

Far better in my opinion to use good quality providers with good equipment, proper maintenance, good multiple bandwidth providers, etc etc. Anyone can come along and say "we guarantee X% uptime" but essentially it's a meaningless statement.

The internet is an amazing collection of technologies and it's incredible sometimes that it keeps on working! After being around the net for a while you realise that something somewhere is bound to go wrong sometime, what's crucial is how the folk concerned deal with the issue when it happens.

The best people leap into action right away and get it sorted, without fuss, asap, and keep everyone informed along the way. The worst people (and anyone in the business in the UK can think of a certain large company who advertise a lot...;)) prevaricate, blame other people, don't tell you what's happening and take forever to get the problem fixed.

/rant :D

Absolutely spot on Chris.

Slashdot Article With Link (http://slashdot.org/article.pl?sid=02/07/09/209241&mode=thread&tid=95)

There you go.

Frankly I agree with most of the article, it's very similar to what I've seen myself.

That's a great article!

I've helped run really class-act server farms in EMC and Exodus data centers, redundant Sun's, redundant pipes, redundant routing. $200,000 a month hosting cost type stuff, and uptime on the web site (notice not plural) hosted was maybe, and I mean maybe, 99.8-99.9% what with Oracle woes, stupid NES tricks, and DoS's helping keep the % down.

Trying for 99.9+ on a server hosting hundreds of web sites is admirable but likely not attainable.

Not for $3.95 a month, or $15.95 a month. I've thought about doing a fully redundant server farm for truly awesome uptime hosting offerings, but hell I'd have to charge $30 or 40 a month for a simple web site to make it viable.

And you'd have to sell the hell out of it.

Shared hosting just doesn't seem to be the right path for that kind of reliability guarantee. I agree it's admirable, and even expected that you try, but being honest with your customers is probably a better avenue to take.

"We will try our best, but we cannot guarantee 100% uptime, it just isn't possible." might be a good way to describe it.

In our experience one of the main reasons for downtime is poorly written application code. I can't remember how many times we've had clients complaining of downtime, only to go through their code and point out all the major problem areas - client then fixes the code and uptime improves unbelievably.

That article seems to refer to single server environments, whereas it is not unachievable to reach four or five nines with redundant kit, although achieving 5 nines on a site on a Shared Server with proactive patching that requires restarting of services of reboots is rather more difficult.


Originally posted by DizixCom
And you'd have to sell the hell out of it.

Shared hosting just doesn't seem to be the right path for that kind of reliability guarantee. I agree it's admirable, and even expected that you try, but being honest with your customers is probably a better avenue to take.

"We will try our best, but we cannot guarantee 100% uptime, it just isn't possible." might be a good way to describe it.

Thats the best way - we say 99.9% but go all out to try to get a lot higher.

you can prove to them if your server has been down or not by clicking start run then enter telnet http://yoursite.com then you have to give your password into the site ect.