I find the general assumption among us bloggers is these providers have to be up 99.9999% of the time. Major crisis when any of them has a crisis. Because supposedly that is what corporate America has always got and continues to get.

Who started that myth? Other than some sensitive and global apps, there is plenty of downtime in corporate data centers and those of big outsourcers like IBM and EDS.

In a given year (unlike a leap one like this year), we have 525,600 minutes. To meet a 99.99% uptime, the system could only be down 52 minutes – less than an hour – in the year. I can tell you most corporate data centers have scheduled downtimes which exceed that every month, if not every week.

The mythical 99.99% uptime SLA

Most bloggers of course have never worked a graveyard shift in a data centre, where system availability reports weres74000 written up.  I’ve worked in a data centre, and I worked graveyard shift.  Didn’t care for SARs though

And four 9’s performance (99.99%) performance is rarely achievable.  Why?  Well, systems maintenance windows, hardware failures, & operator errors all conspire against that.  Of course, the clever service provider excludes those events, we certainly did.  Except for the operator errors, which were not many..

Or you can go the expensive route and design your systems to be able to support four 9’s.  It will cost a bundle of money, and may not be that effective (you can’t control risks outside your control).  If you are going to promise high uptimes to a customer, you had better be darn sure that you have the infrastructure and systems to support it.

Tandem NonStop systems rocked!

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