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Zookeeper >> mail # dev >> help! some questions about zk


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聂安 2013-10-21, 08:47
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Alexander Shraer 2013-10-21, 23:48
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Re: help! some questions about zk
(2) You can lose a committed data if have more failure than what the
quorum is configured to support (eg. losing 3 out of 5 hosts)
  
--
Thawan Kooburat

On 10/21/13 4:48 PM, "Alexander Shraer" <[EMAIL PROTECTED]> wrote:

>Hi,
>
>(1) Zab is an atomic broadcast protocol, it satisfies strong ordering
>properties. Check out the paper:
>http://www.stanford.edu/class/cs347/reading/zab.pdf
>
>Its used to propagate updates in the same order to all the ZooKeeper
>servers. The provided consistency in ZooKeeper is basically sequential
>consistency +
>real-time-order on writes. This is strong, although not linearizable
>(its possible that you read from a server that has stale data).
>
>If you use the sync call before a read, ZooKeeper provides
>ilnearizability for sync+read and write operations (this is true with
>certain timing assumption made in ZooKeeper for efficiency).
>
>(2) No, only a suffix of uncommitted operations can disappear.
>Operations acked by a quorum never dissappear.
>
>(3) For read operations the server responds immediately using local
>state. For writes it responds after a quorum acked the update.
>
>
>Alex
>
>On Mon, Oct 21, 2013 at 1:47 AM, 聂安 <[EMAIL PROTECTED]> wrote:
>> hi all,
>>
>> About zk, I got some questions bothered me for one week, which can be
>>described as follows:
>>
>> (1)  Does zab guarantee a strong consistency?
>>
>> (2) Could those committed proposals on new-elected-followers be deleted
>>when initially synced?
>>
>> (3)  When does the server in zk respond to the client? After commiting
>>the proposal?
>>
>> thank you!
>>
>>
>>
>>
>> Regards,
>>
>> An.Nie

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Alexander Shraer 2013-10-22, 00:03
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB