[svlug] 99.99% uptime...

[Alvin Oga]

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
#
#
#......