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From Maxim Muzafarov <maxmu...@gmail.com>
Subject Re: NATIVE PERSISTENCE: Cache data is destroyed after disable WAL and restart
Date Fri, 17 May 2019 13:51:09 GMT
Hello Manu, sorry for the delay.

By disabling WAL for particular cache group you remove any recovery
guarantees in case of node fail for it. It is a normal trade-off
between data loading speed and further recovery. For instance, the
checkpoint thread (a thread which flushes cache data to disk) fails in
the middle its write process we will have two options: start node with
corrupted data (since WAL is disabled and there is no chance to
recover it) and clear all the cache data previously written. It is
better to choose the second option.

What do you think?

On Sun, 28 Apr 2019 at 17:05, Manu <maxnu00@hotmail.com> wrote:
>
> Hi!
>
> I have a question, is it normal that if WAL is deactivated for a persisted
> cache when the server node(s) is restarted, the persisted content of the
> cache is completely destroyed?
>
> I need to disable WAL for large heavy ingestion processes, but eventually
> ingestion may fail (OS, machine crash), so WAL state is not re-enabled after
> ingestion. On this situation if I restart a server node, cache persistent
> directory is deleted and recreated again, so data is lost.
>
> Thanks!
>
> This is the method that do this hell thing
> org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager.beforeCacheGroupStart
>
> Process to replicate it:
>
> 1. Start one or more server nodes with native persistence enabled
> 2. Create a cache (natively persisted) and store some data
> 3. Disable WAL for cache - ignite().cluster().disableWal("TheCacheName")
> 4. Restart server/s nodes
> 5. Check cache directory was deleted and recreated again, all data was lost.
>
> Call stack on server node start:
> *org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager.beforeCacheGroupStart*
> org.apache.ignite.internal.processors.cache.ClusterCachesInfo.registerCacheGroup
> org.apache.ignite.internal.processors.cache.ClusterCachesInfo.registerNewCache
> org.apache.ignite.internal.processors.cache.ClusterCachesInfo.processJoiningNode
> org.apache.ignite.internal.processors.cache.ClusterCachesInfo.onStart
> *org.apache.ignite.internal.processors.cache.GridCacheProcessor.startCachesOnStart*
> org.apache.ignite.internal.processors.cache.GridCacheProcessor.onReadyForRead
> org.apache.ignite.internal.processors.cache.persistence.GridCacheDatabaseSharedManager.notifyMetastorageReadyForRead
> org.apache.ignite.internal.processors.cache.persistence.GridCacheDatabaseSharedManager.readMetastore
> org.apache.ignite.internal.processors.cache.persistence.GridCacheDatabaseSharedManager.notifyMetaStorageSubscribersOnReadyForRead
> org.apache.ignite.internal.IgniteKernal.start
> org.apache.ignite.internal.IgnitionEx$IgniteNamedInstance.start0
> org.apache.ignite.internal.IgnitionEx$IgniteNamedInstance.start
> org.apache.ignite.internal.IgnitionEx.start0
> org.apache.ignite.internal.IgnitionEx.startConfigurations
> org.apache.ignite.internal.IgnitionEx.start
> org.apache.ignite.internal.IgnitionEx.start
> org.apache.ignite.internal.IgnitionEx.start
> org.apache.ignite.internal.IgnitionEx.start
> org.apache.ignite.Ignition.start
> org.apache.ignite.startup.cmdline.CommandLineStartup.main
>
> Ignite version 2.7.0
>
>
>
> --
> Sent from: http://apache-ignite-developers.2346864.n4.nabble.com/

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