ignite-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Alexey Kukushkin <alexeykukush...@yahoo.com>
Subject Re: Persistent store and eviction policy.
Date Thu, 10 Aug 2017 08:59:32 GMT
Hi,
1. Persistence and Data Eviction are alternative options to handle out-of-memory scenarios.Persistence
makes Ignite fill all available RAM and move the oldest page to the “disk” part of the
cache when there is not enough memory.
Data eviction policy makes Ignite to completely remove some entries or memory pages from the
cache depending on the policy.Persistence comes at cost of performance but gives us virtually
unlimited reliable cache.Use the one or the other.

2. No, if you have no backups configured and a node goes down the data becomes unavailable.
Persistence will not help - only partitions that a nodes owns are persisted on the node. Configure
backups to address the issue.
Best regards, Alexey


On Thursday, August 10, 2017, 5:38:50 AM GMT+3, userx <gagansab@gmail.com> wrote:

Hi team,

I was going through the documentation of durable memory at
https://apacheignite.readme.io/docs/durable-memory

As per the documentation, durable memory comes into picture when
PersistentStore configuration is enabled. Now durable memory uses both
RAM(hot data) and disk (superset). When the RAM part reaches a threshold
(80% by default as per the documentation), the durable data retains only hot
data in RAM and rest on the disk.

QUESTION 1
So does that mean that there is a default eviction policy which comes into
existence ? Or does the user explicitly has to mention the same in
configuration ? What happens if he does not mention the eviction policy in
configuration ?

Suppose there are 2 nodes N1 (different physical box) and N2 (different
physical box) and the data is distributed in PARTITIONED mode and persistent
store is enabled. 

Here is the example of entries

N1-> "1","X"
N2-> "2","Y"

QUESTION 2
Suppose N1 crashes and goes down and does not come up at all for say 5
hours. Is "1" retrievable at all during that time if N1 went down after an
entry to its WAL file or we loose N1 ? If say the entry was not able to be
made in WAL file and should we have configured a back up as N3 (different
physical box), would it have saved "1" ?







--
View this message in context: http://apache-ignite-users.70518.x6.nabble.com/Persistent-store-and-eviction-policy-tp16092.html
Sent from the Apache Ignite Users mailing list archive at Nabble.com.

Mime
View raw message