Hi Henrik and Matteo, While I agree with Henrik: increasing your replication factor won’t improve recovery or read performance on its own. If you are changing from replica 2 to replica 3, you might need to scale-out your cluster to have enough space for the additional replica, and that would improve the recovery and read performance.
Cheers, Maxime From: ceph-users <[email protected]> on behalf of Henrik Korkuc <[email protected]> Date: Friday 3 March 2017 11:35 To: "[email protected]" <[email protected]> Subject: Re: [ceph-users] replica questions On 17-03-03 12:30, Matteo Dacrema wrote: Hi All, I’ve a production cluster made of 8 nodes, 166 OSDs and 4 Journal SSD every 5 OSDs with replica 2 for a total RAW space of 150 TB. I’ve few question about it: * It’s critical to have replica 2? Why? Replica size 3 is highly recommended. I do not know exact numbers but it decreases chance of data loss as 2 disk failures appear to be quite frequent thing, especially in larger clusters. * Does replica 3 makes recovery faster? no * Does replica 3 makes rebalancing and recovery less heavy for customers? If I lose 1 node does replica 3 reduce the IO impact respect a replica 2? no * Does read performance increase with replica 3? no Thank you Regards Matteo -------------------------------------------- This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. _______________________________________________ ceph-users mailing list [email protected]<mailto:[email protected]> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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