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cluster-of-clusters WIP

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Scott Lystig Fritchie 2015-06-17 10:56:22 +09:00
parent a8c914a280
commit ce583138a9
1 changed files with 7 additions and 7 deletions
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14
doc/cluster-of-clusters/name-game-sketch.org
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@ -134,7 +134,7 @@ Assume that we have a random slicing map called ~Map~. This particular
| 0.66 - 0.91 | Cluster3 |
| 0.91 - 1.00 | Cluster4 |
Then, if we had CoC file name ="foo"=, the hash ~SHA("foo")~ maps to about
Then, if we had CoC file name "~foo~", the hash ~SHA("foo")~ maps to about
0.05 on the unit interval. So, according to ~Map~, the value of
~rs_hash("foo",Map) = Cluster1~. Similarly, ~SHA("hello")~ is about
0.67 on the unit interval, so ~rs_hash("hello",Map) = Cluster3~.
@ -177,13 +177,13 @@ the head of Cluster2 (which the client magically knows how to
contact), then the result will look something like
~{ok,"foo.s923.z47",ByteOffset}~.
So, ~ "foo.s923.z47" ~ is the file name that any Machi CoC client must use
in order to retrieve the CoolData bytes.
Therefore, the file name "~foo.s923.z47~" must be used by any Machi
CoC client in order to retrieve the CoolData bytes.
*** Problem #1: We want CoC files to move around automatically
If the CoC client stores two pieces of information, the file name
~ "foo.s923.z47" ~ and the Cluster ID Cluster2, then what happens when the
"~foo.s923.z47~" and the Cluster ID Cluster2, then what happens when the
cluster-of-clusters system decides to rebalance files across all
machines? The CoC manager may decide to move our file to Cluster66.
@ -257,7 +257,7 @@ What if the CoC client uses a similar scheme?
1. CoC client has ~p.s.z.A~ and parses the parts of the name.
2. Coc calculates ~rs_hash(p.s.z.A,Map) = T~
3. CoC client requests @ cluster ~T~: ~read(p.s.z,...) -> ~ ... success!
3. CoC client requests @ cluster ~T~: ~read(p.s.z,...) ->~ ... success!
** The details: calculating 'A', the adjustment factor
@ -300,10 +300,10 @@ easily fixable but just not written yet.
1. We start with a file name, ~p.s.z.A~. Parse it.
2. Calculate ~SHA(p.s.z) = H~ and map H onto the unit interval.
3. Decode A, then calculate M = A - H. M is a ~float()~ type that is
3. Decode A, then calculate ~M = A - H~. ~M~ is a ~float()~ type that is
now also somewhere in the unit interval.
4. Calculate ~rs_hash_after_sha(M,Map) = T~.
5. Send request @ cluster ~T~: ~read(p.s.z,...) -> ~ ... success!
5. Send request @ cluster ~T~: ~read(p.s.z,...) ->~ ... success!
*** The bad way: file write