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Questions tagged [downtime]

The term downtime is used to refer to periods when a system is unavailable.

Downtime refers to a period of time that a system fails to provide or perform its primary function.

Reliability, availability, recovery and unavailability are related concepts. The unavailability is the proportion of a time-span that a system is unavailable or offline. This is usually a result of the system failing to function because of an unplanned event, or because of routine maintenance (a planned event).

The term is commonly applied to networks and servers. The term is also commonly applied in industrial environments in relation to failures in industrial production equipment.

Some facilities measure the downtime incurred during a work shift, or during a 12 or 24-hour period. Another common practice is to identify each downtime event as having an operational, electrical or mechanical origin.

The opposite of downtime is uptime.

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Erlang's 99.9999999% (nine nines) reliability

Erlang was reported to have been used in production systems for over 20 years with an uptime percentage of 99.9999999%. I did the math as the following: 20*365.25*24*60*60*(1 - 0.999999999) == 0.631 s That means the system only has less than one…
Ning
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Is there a smarter way to reindex elasticsearch?

I ask because our search is in a state of flux as we work things out, but each time we make a change to the index (change tokenizer or filter, or number of shards/replicas), we have to blow away the entire index and re-index all our Rails models…
concept47
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Zero downtime on Heroku

Is it possible to do something like the Github zero downtime deploy on Heroku using Unicorn on the Cedar stack? I'm not entirely sure how the restart works on Heroku and what control we have over restarting processes, but I like the possibility of…
brad
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What does a unicorn image on Github.com mean?

I went to view my repository on Github.com and was presented with a giant pink unicorn and a message saying: No server is currently available to service your request. Does this mean something is wrong with my repository or account? Have I made in…
Brett DeWoody
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Detecting if the JQuery CDN is down and coping with it

I'm launching my own site tomorrow, and I'm expecting a couple hundred visits. I wrote this script based on what PHP.net told me:
Karan
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Zero downtime/blue-green deployment of Single Page Application (SPA)

Yesterday together with the team we were discussing the possibility of using zero downtime deployments to support our single page application. While discussing it we identified one edge case for it. After user loads the page in his browser it cannot…
gerichhome
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What is the difference between failover vs high availability?

According to my reading on jboss documentation it says, We define high availability as the ability for the system to continue functioning after failure of one or more of the servers. A part of high availability is failover which we define as…
Techie
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Altering MySQL InnoDB table with minimal downtime

I've got a huge InnoDB table(>500 millions rows) which I'd like to partition by hash in order to decrease the index size. I'd like to achieve this with a minimal downtime(e.g 10 minutes is acceptable), what are the possible options? I was thinking…
pachanga
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Achieving zero downtime Cassandra/DataStax migrations

I've got a Cassandra cluster (3 nodes, all nodes deployed to AWS) that I am trying to migrate over to a DataStax cluster. It's simply time to stop managing these nodes myself. I have multiple producers and consumers all reading/writing data, all day…
smeeb
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Is there downtime involved when using Azure vertical scaling?

I have a two websites on a VM with WHM/cPanel and MySql. I am looking to move this into Azure and use vertical scaling. Visits to the website are usually stable but three or four times a year there is a big increase in traffic which historically has…
stepeng
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Migrating `int` to `bigint` in PostgresSQL without any downtime?

I have a database that is going to experience the integer exhaustion problem that Basecamp famously faced back in November. I have several months to figure out what to do. Is there a no-downtime-required, proactive solution to migrating this column…
jefflunt
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gracefully upgrading a website

Is there a preferred method of gracefully upgrading a web site? I have a completely new code base ready to go on a site, but updating it will take several hours. I don't want the site to be down the entire time with a "Upgrading, be back soon!"…
Brad
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Kubernetes rolling update without downtime?

According to https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#scaling-a-statefulset, I would like to ask how to achieve zero-downtime rolling update? I guess here are the minimum requirements: (1) .spec.updateStrategy…
Kok How Teh
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How to calculate application availability (SLA)

I have standard ASP.NET MVC project and I need to calculate application availability to find out our SLA level. So, I need to get something like this for our web application. Information from my hosting provider System Availability:…
Roman Marusyk
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App Engine downtime

Does Google's App Engine have excessive downtime, specifically with regards to datastore writes? Additionally, downtime seems to be scheduled during high traffic times, e.g., in the middle of the afternoon vs. 3:00AM in the morning. Is this normal?…
Chris Dutrow
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