Folks, I’ve updated the documentation avoiding any misunderstanding - " If Ignite Persistence is enabled then the page-based evictions have no effect because the oldest pages will be evicted from RAM automatically if there is not enough space available.”
https://apacheignite.readme.io/v2.1/docs/evictions <https://apacheignite.readme.io/v2.1/docs/evictions> BTW, why can’t we make the eviction customizable when the store is used? Don’t see any issue with that from the user perspective. — Denis > On Aug 10, 2017, at 2:18 AM, Ivan Rakov <ivan.glu...@gmail.com> wrote: > > Hi! > > > I'm afraid, description of page-based eviction in documentation is not quite > correct. > Page-based eviction (RANDOM_LRU or RANDOM_2_LRU) can be activated only if > persistent store is disabled. It defines algorithm for choosing page in RAM > to remove all contents completely. > On the other hand, when persistent store is enabled, eviction from RAM to > disk is enabled by default and is not customizable by user. So answer to > first question 1 is no - you shouldn't specify anything in configuration to > make disk eviction work. > > About question 2 - You will lose partition after crash of N1. Losing of > partition is always undesirable scenario. By default, partition will be > reset, and you can't say for sure which version of partition (old from disk > or new from another node) will be resolved as actual after join of N1. > Safe solution - configure backup nodes. Your data will be safe at N3. > Another safe solution - set safe partition loss policy (e.g. > PartitionLossPolicy.READ_WRITE_SAFE). All reads/writes from lost partition > will throw an exception until crashed node N1 returns to the topology. After > that, "1" entry will be recovered. > > > Thanks for raising this topic, we'll fix the documentation soon. > Best Regards, > Ivan Rakov > > On 10.08.2017 5:38, userx wrote: >> Hi team, >> >> I was going through the documentation of durable memory at >> https://apacheignite.readme.io/docs/durable-memory >> <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 >> >> <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. >
