We went to 3 copies because 2 isn't safe enough for the default. With 3 copies and a properly configured system your data is approximately as safe as the data center it's in. With 2 copies the durability is a lot lower than that (two 9s versus four 9s or something). The actual safety numbers did not otherwise change materially for the firefly release, though. -Greg
On Monday, December 7, 2015, Le Quang Long <[email protected]> wrote: > Hi all, > > I have one question > > Why did default replication change to 3 in Ceph Firefly? I think 2 copys > of object is enough for backup. And increase the number of replication also > increase latency when object has to be replicated to secondary and tertiory > OSD. > > So why default replication is 3, not 2 or 4 or other numbers? > > Thanks and regards. > > >
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