7 ms·
This article made me contemplate that pure uptime percentage is not the best way to measure availability. Surely having 5 to 10 second outages 10 times a month
by mikeknoop 16y ago
This article made me contemplate that pure uptime percentage is not the best way to measure availability. Surely having 5 to 10 second outages 10 times a month is better than having a single outage for 4 hours?
- corin_ 16y agoWhile your second statement is true, uptime percentage remains the best way until somebody suggests a new (feasible) method.
- hammerdr 16y agoA combination of both uptime percentage and mean outage time (or mean time between outages.. which is essentially the same thing).
- wmf 16y agoYes, that's why many SLAs do not count short outages.
- ceejayoz 16y agoI'd be pretty mad if that was in my SLA, unless it was very carefully worded. If the system's going down for a minute every hour or two, it's probably more of a disruption to me than if it goes down for an hour or two once a month.
- lutorm 16y agoI don't understand your point: 10 x 10s outages = 100s downtime. One 4h outage = 14000s downtime. Uptime percentage agrees with you that the former is better.
- mikeknoop 16y agoSorry for the poor math -- You would have to have roughly 100 10 second outages each month to approach a 4 hour outage one a year.
- wmf 16y agoThe original example wasn't very good, but try this one: would you prefer 240 1-minute outages or one 4-hour outage?
- deleted 16y ago[deleted]
- nickolai 16y agoI'm not sure that beyond 1 minute or so it actually matters whether it is 2 minutes or 2 hours. The system is down. Period. The average user will acknowledge that the system is down and will try again in several hours. From this perspective, it is definitely better to have one big 2-hour outage than a ton of small 2-minute ones. (EDIT) Saw someone post something like "miltiple small downtimes erode the user's belief in system stability". too bad he deleted the message : it was nailed spot on!
- smackfu 16y agoI don't know if I agree that the average user will try again in several hours. There is a big difference if my email is down for 5 minutes or an hour, if I need to check something now, since "now" includes 5 minutes from now but likely not an hour.
- JoeAltmaier 16y agoClients automatically retry. The real issue is timeliness of email delivery - as long as you can compose and register email, all that's left is getting it read. I noticed they don't mention the reliability of delivery - how many email are lost? Elephant on the table.