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Posted: Sun, 03/14/2010 - 14:25
hi,
Im currently working on my diploma thesis and eucalyptus is one of the products I describe in it. Im just about to explain the different components and have difficulties with the difference of the SC and walrus. In some resources it says they are two different things, some state they are the same?!? can anybody help me out on this???
thanks, christine
Posted: Mon, 03/15/2010 - 01:29
Hi neil,
thx for the answer. so can I actually use both of them simultanously oder do I use one OR the other?
the other source I used was this pdf http://open.eucalyptus.com/documents/ccgrid2009.pdf. It doesnt literally say they are the same but they are listed under the same headline and theres no difference between them stated.
Posted: Mon, 03/15/2010 - 22:00
Hello,
they are different components and you can use them at the same time: typically walrus is co-located with the clc and the sc is co-located with the cc, and in a single cluster case, they are typically located on the same machine, the frontend.
cheers
graziano
Posted: Sat, 03/20/2010 - 16:41
thx for the answer.
in the paper stated above I found the following description:
"Walrus is entrusted with the task of verifying and decrypting images that have been uploaded by users. When a node controller (NC) requests an image from Walrus before instantiating it on a node, it sends an image download request that is authenticated using an internal set of credentials. Then, images are verified and decrypted, and finally transferred. As a performance optimization, and because VM images are often quite large, Walrus maintains a cache of images that have already been decrypted. Cache invalidation is done when an image manifest is overwritten, or periodically using a simple least recently used scheme."
this description is stated under the headline "storage controller (walrus)", so I was wondering does this refer now only to walrus? or is the explanation valid for both walrus and SC??? Im still a bit confused about the separation of the two and cant find a detailed description anywhere.
Posted: Sat, 03/20/2010 - 18:15
The naming is rather unfortunate. In the paper, "storage controller" was a generic term used to denote the part of Eucalyptus that provided storage support (at the time, it was only Walrus/S3 API). When that paper was written, Eucalyptus did not have dynamic block storage (EBS API) support. When we did add support for block storage, the component in charge of it was called the "Storage Controller" (proper noun). Rather unfortunate and hopefully that paper is the only document where this confusion manifests. That paper is out of date at this time. although the concepts are still true.
hope that helps
neil
Posted: Sun, 03/14/2010 - 16:05
They are different components. The SC provides EBS-api compatible functionality and Walrus provides S3-api compatible functionality. Can you point to the resource that says that they are the same? If so, it needs to be fixed.