Thanks a lot for your clarification, John. This issue was raised by some of 
CloudStack S3 customers, and they are questioning why we didn't display the 
usage information for their S3 secondary storage in CloudStack Dashboard UI, 
which includes both size of objects in the bucket and physical space in the 
cluster a bucket occupies. I totally agree with you that these will be vendor 
specific, and we should not bother to display them on CloudStack UI.

Thanks
-min

From: John Burwell <jburw...@basho.com<mailto:jburw...@basho.com>>
Date: Wednesday, January 15, 2014 10:42 AM
To: Min Chen <min.c...@citrix.com<mailto:min.c...@citrix.com>>
Cc: "dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>" 
<dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>>, Thomas O'Dowd 
<tpod...@cloudian.com<mailto:tpod...@cloudian.com>>
Subject: Re: S3 API to get S3 bucket usage data?

Min,

Such a notion is completely anachronistic to a client object store due to the 
abstraction — it is solely an operational.  Hence, you won’t find space 
information available in object store client APIs.

The first question is what space information are you seeking?  The logical size 
of the objects in the bucket or how much physical space in the cluster a bucket 
occupies?  The first is simply a sum of all object sizes in the bucket.  The 
second is very difficult to answer through the client interface due to factors 
such as the intra-cluster replication factor for the bucket, the use of 
mechanisms such as erasure encoding and compression, and the number of data 
centers to which the object is replicated. For these reasons, space information 
is typically only exposed via the operational monitoring interfaces, and would 
likely need to be acquired through vendor specific drivers.

Thanks,
-John

On Jan 15, 2014, at 1:27 PM, Min Chen 
<min.c...@citrix.com<mailto:min.c...@citrix.com>> wrote:

Hi there,

Does anybody out there know if AWS S3 provides programmatical way to get 
bucket-level usage data? For example, used space or available space as we 
current show in CloudStack dashboard for NFS secondary storage. I googled 
around the web, and didn't find any S3 api to do that. Any comments will be 
appreciated.

Thanks
-min

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