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Questions tagged [paxos]

Paxos is a family of protocols for a network of unreliable processors to agree on a result.

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Why does the proposer sends an accept request with the same value it got from the acceptor?

In the second phase of the paxos algorithm, the proposer issues an accept request with the number n and the value v it got from the acceptor, if the acceptor has already chosen a value previously. My questions is why the proposer is doing this?…
fluter
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how eureka peers guarantee the registration information is consistent when sync action fail

PeerAwareInstanceRegistryImpl will sync to other peers when registration changed,the code as follows: private void replicateInstanceActionsToPeers(Action action, String appName, String id, InstanceInfo…
wangsan
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Is a replication log necessary to achieve linearizability in distributed store

The Raft algorithm used by etcd and ZAB algorithm by Zookeeper are both using replication log to update a state machine. I was wondering if it's possible to design a similar system by simply using leader election and versioned values. And why those…
skyde
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Multiple IF conditions in Cassandra lightweight transactions/CAS

So I'm trying to do a CAS (compare-and-set) type operation in Cassandra, where I want to do a data update only if a particular non-primary-key column is NULL or < ? where ? is supplied by client-side code. How do I do this? Something like the…
Nishant Kelkar
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Light Weight Transactions (LWT) failing while new nodes join cluster

I had a 9 node cluster running Cassandra 2.0.12 (DataStax Community edition). I had to expand this cluster so added 3 more nodes following the DataStax advised as per…
dwivedialok
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Why paxos acceptor must send back any value they have already accepted

I'm learning MIT 6.824 class and I have a question about paxos. When proposer send a prepare to acceptor, acceptor will return a prepare_ok with n and v which highest accept see. I wonder why acceptor need to return n and v?
modkzs
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Using Paxos to synchronize a large file across nodes

I'm trying to use Paxos to maintain consensus between nodes on a file that is around 50MB in size, and constantly being modified at individual nodes. I'm running into issues of practicality. Requirements: Sync a 50MB+ file across hundreds of…
TheEnvironmentalist
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Spanner's Read-Only Transaction

I do understand Spanner's read-only transaction in one paxos group. But how does the read-only transaction over more than one paxos group work? The paper says that it uses TT.now().latest as timestamp which then performs a snapshot read with the…
user1091344
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Two-phase commit vs Paxos

I am quite confused with these two technologies. Are there any relationship between these two technologies Are there any existing popular open source software implements these technologies? I know zookeeper implements Paxos but what about Two-phase…
Howard
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How does one handled skipped event numbers with Paxos?

If we are running multi-paxos then a node may see: Propose(N) Accept!(N,Vn) Accept!(N+1,Vm) Accept!(N+4,Vo) // huh? where is +2, +3? Accept!(N+5,Vp) This may be because either: There was a stable leader but the network local to this node dropped…
simbo1905
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In "Part-time Parliament" why does using the membership from decree n-3 work to add or remove members?

Section 3.3.6 of "The Part-Time Parliament" suggests that membership in the parliament (and thus the quorum for decisions) can be changed safely "by letting the membership of Parliament used in passing decree n be specified by the law as of decree…
djmitche
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Why is Chubby lockserver not multi-master?

As I understand Chubby at any given time there are 5 chubby servers. One is the master and handles coordination of writes to the quorum, and the other 4 servers are read only and forward handling of writes to the master. Writes use Paxos to maintain…
user782220
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Model checking Paxos

I have implemented consensus algorithm (based on Paxos). I have added some random test cases and it seems fine. But want to do testing via model check? Couldn't find correct article for it. Please share how to do about model checking in Paxos Thanks
mohan
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Performance of LWT in scylla/cassandra

Wanted to understand the why do we say the throughput of whole Cassandra/scylla/cockroachDB setup is dependent on LWT/linearised TX. LWT will affect throughput of a hot key (index or row with a lot of queries), I do understand we can't increase…
siddharthabhi30
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The relationship between Paxos family and data consistency

Paxos, a kind of consensus algorithm, plays a vital role in distributed database systems. It can be used to make the distributed system chooses the same proposal. Data consistency is a big problem in the database system. Others consisder that Paxos…
dengzeyuan
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