openstack team mailing list archive

[John Purrier <john@xxxxxxxxxxxxx>]

This is great info, John. Thanks.

John

John Purrier
john@xxxxxxxxxxxxx
(206) 930-0788
http://www.linkedin.com/in/johnpur





On 8/10/12 9:31 AM, "John Dickinson" <me@xxxxxx> wrote:

>In a standard swift deployment, the proxy server is running behind a load
>balancer and/or an SSL terminator. At SwiftStack, we discovered an issue
>that may arise from some config parameters in this layer, and we'd like
>to share it with other swift deployers.
>
>Symptom:
>
>Users updating metadata (ie POST) on larger objects get 503 error
>responses. However, there are no error responses logged by swift.
>
>Cause:
>
>Since POSTs are implemented, by default, as a server-side copy in swift
>and there is no traffic between the user and swift during the server-side
>copy, the LB or SSL terminator times out before the operation is done.
>
>Solution:
>
>Two options:
>
>1) Raise the timeout in the LB/SSL terminator config. For example, with
>pound change the "TimeOut" for the swift backend. pound defaults to 15
>seconds. The appropriate value is however log it takes to do a server
>side copy of your largest object. If you have a 1gbps network, it will
>take about 160 seconds to copy a 5GB object ((8*5*2**30)/((2**30)/4) --
>the divide by 4 is because the 1gbps link is used to read one stream (the
>original) and write the new copy (3 replicas)).
>
>2) Change the behavior of POSTs to not do a server-side copy. This will
>make POSTs faster, but it will prevent all metadata values from being
>updated (notably, Content-Type will not be able to be modified with a
>POST). Also, this will not make the issue go away with user-initiated
>server-side copies.
>
>I would recommend the first solution, unless your workload makes heavy
>use of POSTs.
>
>Hoep this helps.
>
>--John
>
>
>_______________________________________________
>Mailing list: https://launchpad.net/~openstack
>Post to     : openstack@xxxxxxxxxxxxxxxxxxx
>Unsubscribe : https://launchpad.net/~openstack
>More help   : https://help.launchpad.net/ListHelp