22 September 2007

dCache update

I was speaking to Tigran from dCache during CHEP and got some new information about dCache and Chimera.

First off, ACLs are coming, but these are not tied to Chimera. They are implementing NFS4 ACLs, which are then mapped to POSIX, which (according to Tigran) makes them more like NT ACLs. Need to look into this further.

Secondly, the dCache guys are really pushing the NFS v4.1 definition as they see it as the answer to their local data access problems. 4.1 clients are being implemented in both Linux and Solaris (no more need to dcap libraries!). According to Tigran, NFS4.1 uses transactional operations. The spec doesn't detail the methods and return codes exactly. Rather, it defines a set of operations that can be combined into a larger operation. This sounds quite poweful, but how will the extra complexity lead to client-server interoperation?

Finally, one thing which I had realised about Chimera is that it allows you to modify the filesystem without actually mounting it. There is an API which can be used.

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