[Openstack] Openstack Shift Write Minimum Node requirement

John Dickinson me at not.mn
Tue Feb 13 16:51:51 UTC 2018


This sounds like expected behavior with 3 storage nodes. In order for a write to successfully complete, it must be written to a quorum of storage devices. In the case of 3 replicas, the quorum is 2. By writing to two drives, Swift is providing some guarantees about the durability and availability of the data. A single copy is not durable, so a write to only a single drive will never return success to the client.

This means that you need at least 2 drives available in order to write to a 3 replica policy.

--John




On 13 Feb 2018, at 3:21, aRaviNd wrote:

> Hi All,
>
> We have configured swift with one proxy and three storage nodes. Our setup
> contain two regions and three zones.
>
>
> ‚Äč
> When two nodes goes down we are not able to upload any files but download
> and read is working fine. Is there any requirement for minimum no of
> storage nodes required for write to work?
>
> Aravind M D


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