[svlug] 99.99% uptime...

[hvrietsc@yahoo.com]

usually the server being available 99.99999 or whatever % is not the issue
what the user really wants is his/her data and the services on them
to be always available. to do this you need to a whole bunch of belts and suspender stuff:

dynamic multipathing to the data: two physical ways to get to your data in case one breaks
HA clustering: more than one machine in case one dies with automatic failover of all relevant
services
clustering filesystem: so you can have the same filesystem available to all clustermembers
journaling filesystem: so that if all else fails you do not need fsck
replication of data: so if journaling fails you can get the data from someplace else

i know of a company that sells all this stuff and it works the same across solaris, hp-ux, nt
and soon linux,but i forgot the name ;-)


On Sun, Oct 15, 2000 at 06:44:33PM -0700, Alvin Oga wrote:
> 
> hi ya....
> 
> some folks seem to want to provide 99.9999% uptime...
> ( new kids(company) on the block )
> 
> so i wanted to see what that means....
> 
> lets pretend that a server goes down for only 15 minutes
> for whatever reason....swapp disks...add memory...
> disk crash ..etc..etc...
> 
> I claim the marketing folks going around quoting 99.9999%
> uptime is insane ????
> 	- guess i'll pass on that company....
> 
> you'd have to keep that puppy up and running for 8 years and
> still couldnt reach 99.9999% uptime...
> non-stop except for 14 minutes.....
> 	- how long does a reboot of the system takes ???
> 	- how long does it take to e2fsck the 40Gb or 500Gb disks ???
> 		- not much time for "maintenance"
> 	- dont forget the kernel ticks tooo...( dies at 4xx days )
> 	- and dont forget too that you have to drive to get to that dead box
> 
> -- adding more machines in the cluster for "HA" makes the problem
>    even more complex ???? ( orders of magnitude easier to keep
>    one server up and running and guaranteeing data saved onto 
>    secondary backup hot-swap box that is also up and running
>    	- change the ip# and your dead box is replaced ...
> 
> c ya
> alvin
> 
> 
> -------------------------------------------------------------------
> assume....14 minutes of down time.... for the life of the server...
> -------------------------------------------------------------------
> #
> # Daily...                      downtime...     uptime...
> # --------
> # 1,440 minutes per Day....     0.972222%       99.0278% uptime
> #
> #
> # Weekly...
> # ----------
> # 10,080 minutes per Week...    0.138888%       99.8611% uptime
> #
> #
> # Monthly...( 30 days )
> # ----------
> # 43,200 minutes per Month...   0.032407%       99.9676% uptime
> #
> #
> # still reasonable... uptimes...
> #
> #
> # Quarterly... ( 90 days )
> # ------------
> # 129,600 minutes per Quarter...0.010802%       99.9892% uptime
> #
> #
> # Annually... ( 365 days )
> # -----------
> # 525,600 minutes per Quarter...0.002664%       99.9973% uptime
> #
> #
> #1,051,200 minutes per 2yrs.....0.001332%       99.9987% uptime
> #2,102,400 minutes per 4yrs.....0.000666%       99.9993% uptime 
> #4,2048000 minutes per 8yrs.....0.000333%	99.9997% uptime
> #
> #
> #......
> 
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