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 <gagan...@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.