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From Jan Lehnardt <>
Subject Re: Behavior in event of disk i/o errors?
Date Thu, 01 Jan 2015 11:43:31 GMT

> On 01 Jan 2015, at 12:30 , jumbo jim <> wrote:
> Cluster of unreliable commodity hardware.
> Given the nature of master/master replication, I would imagine that you
> could run cluster nodes without any form of raid?

This is a calculation of odds: how likely is it that your node fails vs.
how likely is it that raid fails vs. how likely it is that a single disk
fails, vs. how expensive is it to run either of these. All of this depends
on your setup, data and budget, but your suggestions might fit your setup.

> As document commits are "all or nothing", I would assume that auto
> replication would not occur if io errors were experienced.
> How might couchdb behave in the event of io errors during reads?

we checksum data on disk and throw errors if the underlying blocks have

E.g. if you have an i/o error (of the nature that a block on disk was
flipped behind the back of CouchDB), that error will not replicate to
any replication targets.


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