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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 | | 0.66 - 0.91 | Cluster3 |
| 0.91 - 1.00 | Cluster4 | | 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 0.05 on the unit interval. So, according to ~Map~, the value of
~rs_hash("foo",Map) = Cluster1~. Similarly, ~SHA("hello")~ is about ~rs_hash("foo",Map) = Cluster1~. Similarly, ~SHA("hello")~ is about
0.67 on the unit interval, so ~rs_hash("hello",Map) = Cluster3~. 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 contact), then the result will look something like
~{ok,"foo.s923.z47",ByteOffset}~. ~{ok,"foo.s923.z47",ByteOffset}~.
So, ~ "foo.s923.z47" ~ is the file name that any Machi CoC client must use Therefore, the file name "~foo.s923.z47~" must be used by any Machi
in order to retrieve the CoolData bytes. CoC client in order to retrieve the CoolData bytes.
*** Problem #1: We want CoC files to move around automatically *** Problem #1: We want CoC files to move around automatically
If the CoC client stores two pieces of information, the file name 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 cluster-of-clusters system decides to rebalance files across all
machines? The CoC manager may decide to move our file to Cluster66. 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. 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~ 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 ** 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. 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. 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. now also somewhere in the unit interval.
4. Calculate ~rs_hash_after_sha(M,Map) = T~. 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 *** The bad way: file write