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bluesky - disassociation of a file from an IP address

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Subject: Global-Scale Distributed Storage Systems

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  • From: "Josh" <josh AT mercuryfs.net>
  • To: "Bluesky global storage list \(E-mail\)" <bluesky AT franklin.oit.unc.edu>
  • Subject: disassociation of a file from an IP address
  • Date: Thu, 2 Aug 2001 20:02:31 -0700


In answer to the previous email, heres how the disassociation works.

Basic permanent caching:

IP address = file
file = math value set A
file distributed world wide

node 1 verifies from source IP address that file still equals math value set
A.
node 1 broadcasts this updated Information record to its network, and all
nodes on it can continue to use file, because it has not changed.
All nodes within node 1's network will know to use their existing copy. If
file has changed, the math values will be different, and all nodes will need
another copy. Once its downloaded once, it can be distributed in a peer to
peer manner.

Now, take this a step further. Imagine that you receive a file from a
different source, and it generates a set of math values A. You can
transparently associate that file as being the file, because of an identity
function achieved by the math values and symmetric property of equality (if
a=b then b=a). that's location independence. So long as you access the file
by its math values, the source need not be the owner of the file.

That's the key to disassociating a file from an IP address, while keeping it
in sync.

That's the key to distributed cache concurrency. See Figure 9 of the design.

Its nothing special, but the MFS handle formula is special. Its can be made
to apply to any file with a URL.

Figure 8 is the key to the whole design. Basically, a file and its URL can
create all of figure 8. once a file is separated into those 3 records,
that's when all the features become possible. Such as downloading Microsoft
office via a modem, and its slow the first time. The URLs for your copy, or
works copy of office may be different, but that's an Information record
issue. There are simply 2 information records, but it's the same data
records. If you have office installed locally, you can still run the version
from work, thru the modem like, but simply use your local data records. But
so long as those information records are current, you have a cached copy of
the Microsoft office files from work. In this regard, MFS is a network file
system that will be fast enough to be a replacement local file system.
Because the anywhere pc goal says that your pc is the provider of your
files, which are at users.isp.net/john.doe. at first glance, you think your
ISP has to approve of every file change, but that's not the case. Your home
PC is simply granted the access to modify user.isp.net/john.doe files as it
pleases. When your home pc logs onto the internet, it also connects to the
ISP. so you are running a network file system locally. When disconnected
operation gets added, the permanent caching will make it a very simple thing
to do.

Its not a persistent cache, it's a permanent cache. The only reason caching
implies being temporary is because nobody knew how to make it permanent. I
think I did it. If I didn't, please point out why.





  • disassociation of a file from an IP address, Josh, 08/02/2001

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