Home | About | Sematext search-lucene.com search-hadoop.com
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
 Search Hadoop and all its subprojects:

Switch to Plain View
Zookeeper >> mail # user >> Maximum size of a snapshot


+
Sergey Maslyakov 2013-07-16, 03:46
+
Thawan Kooburat 2013-07-16, 04:50
+
kishore g 2013-07-16, 07:21
+
Sergey Maslyakov 2013-07-16, 14:16
+
Flavio Junqueira 2013-07-16, 16:16
+
kishore g 2013-07-16, 17:04
+
Flavio Junqueira 2013-07-16, 19:35
Copy link to this message
-
Re: Maximum size of a snapshot
All servers in the quorum reading the snapshot from disk as part of the
synchronization phase. From Thawan's email it looks like when ever there is
a leader election, all zk servers read the snapshot from disk. I am not
sure why all servers should reload the snapshot from disk as this increases
unavailability time.
On Tue, Jul 16, 2013 at 12:35 PM, Flavio Junqueira <[EMAIL PROTECTED]>wrote:

> The synchronization phase is part of the protocol and we use it to
> guarantee that we expose a consistent view of the state. During the
> synchronization phase, servers do not accept requests.
>
> Which behavior are you proposing we change, Kishore?
>
> -Flavio
>
> On Jul 16, 2013, at 7:04 PM, kishore g <[EMAIL PROTECTED]> wrote:
>
> > Thanks for clarification Flavio. Does this mean during the leader
> election,
> > both reads and writes are not supported?. Do we start a separate
> > thread/jira of changing this behavior?.
> >
> > thanks,
> > Kishore G
> >
> >
> > On Tue, Jul 16, 2013 at 9:16 AM, Flavio Junqueira <[EMAIL PROTECTED]
> >wrote:
> >
> >> The disk state should be the authoritative state of a server, so if I
> >> remember correctly, we load the database as a way of validating the disk
> >> state. I don't claim that this is strictly necessary, but if we are to
> >> change it, then I would need to think this through.
> >>
> >> About leader election, if a leader loses support from a quorum of
> >> followers,
> >> then it will drop leadership. Any event that causes a follower to stop
> >> receiving messages from the leader or the follower to disconnect from
> the
> >> leader will make it stop supporting the current leader.
> >>
> >> -Flavio
> >>
> >> -----Original Message-----
> >> From: Sergey Maslyakov [mailto:[EMAIL PROTECTED]]
> >> Sent: 16 July 2013 16:16
> >> To: [EMAIL PROTECTED]
> >> Subject: Re: Maximum size of a snapshot
> >>
> >> And another extension on top of Kishore's question: do the reelections
> >> happen if the previously elected leader remains in the cluster? In other
> >> words, what events can trigger re-election and the corresponding
> temporary
> >> degradation of the service provided by Zookeeper?
> >>
> >>
> >> Thank you,
> >> /Sergey
> >>
> >>
> >> On Tue, Jul 16, 2013 at 2:21 AM, kishore g <[EMAIL PROTECTED]> wrote:
> >>
> >>> Regarding #2. Is that really true that during leader election every
> >>> machine reloads snapshot data from disk? Any reason why this is needed
> >>> unless it really needs to truncate or undo conflicting transactions
> >> already applied?
> >>>
> >>>
> >>> On Mon, Jul 15, 2013 at 9:50 PM, Thawan Kooburat <[EMAIL PROTECTED]>
> wrote:
> >>>
> >>>> Max snapshot size:
> >>>>
> >>>> Here is my take on these issue,  others feel free to add or correct.
> >>>>
> >>>> 1. Depends on how much RAM your machine has.  Snapshot is should be
> >>>> less than the available RAM since everything is loaded into memory.
> >>>> 2. Depends on what is the availability guarantee that the client
> needs.
> >>>> If there is leader election, every machine need to reload the data
> >>>> from disk. So the quorum will be down for at least the same as
> >>>> snapshot
> >>> loading
> >>>> time. The session timeout on the client side should be at least
> >>>> longer than expected downtime during leader election.
> >>>>
> >>>> --
> >>>> Thawan Kooburat
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> On 7/15/13 8:46 PM, "Sergey Maslyakov" <[EMAIL PROTECTED]> wrote:
> >>>>
> >>>>> I have a couple of sizing questions to the users and developers.
> >>>>> Hope,
> >>> you
> >>>>> don't mind answering those.
> >>>>>
> >>>>> What is the guideline for the maximum reasonable size of a DataTree
> >>> that a
> >>>>> single ZK server can manage? If ZK server writes out a snapshot of
> >>>>> about 1GB in size, is it pushed beyond the limits or is it still
> >> manageable?
> >>> If
> >>>>> so, where is the critical threshold when ZK is really being abused?
> >>>>>
> >>>>> Similarly, how can I estimate the propagation delay of a change
+
Thawan Kooburat 2013-07-16, 22:45
+
kishore g 2013-07-17, 01:46
+
Thawan Kooburat 2013-07-17, 03:40
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