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From Andrey Mashenkov <andrey.mashen...@gmail.com>
Subject Fwd: Query performance against table with/out backup
Date Fri, 27 Oct 2017 14:46:25 GMT
Crossposting to dev.


For now we allow user to change number of backups in configuration between
grid restarts with no error.
An user see new configuration object from code, but see old in visor.

So, if user rise number of backups between grid restarts, it will be able
to start the grid successfully.
Seems, then user see more backups in cacheConfiguration then really Ignite
will have.

I slightly rework our persistence examples to check this case and it looks
to be a true.
I see new configuration on client and on servers, but backups=2 can't
prevent data loss in case of 2 nodes failed.

Steps to reproduce (I waited for awhile at each step for rebalance had been
1. Start grid with backups=1 and persistence enabled.
2. Fill with data and shutdown a grid.
3. Change config with backup=2.
4. Start grid and wait for awhile.
5. Kill 2 nodes and observe data loss.

[1] https://issues.apache.org/jira/browse/IGNITE-6781

---------- Forwarded message ----------
From: blackfield <charles.katili@maxpoint.com>
Date: Thu, Oct 19, 2017 at 9:29 PM
Subject: Re: Query performance against table with/out backup
To: user@ignite.apache.org

Here, I am trying to ascertain that I set backup == 2 properly as I
above that I do not see query performance difference between backup ==1 and
backup == 2.

I want to make sure that I configure my cache properly.

When I set the backup==2 (to have three copies), I notice the following via

The Affinity Backups is still equal to 1. Is this a different property than
number of backups? If it is not, how do one see the number of backups a
cache is configured for?

Invoking "cache -a" to see the detail cache stat, with backup==2, under the
size column, the sum of entries on all nodes is equal to the number of rows
in the table * 2.  It appears this is the case for backup >= 1?

As in, only one set of backup will be stored in off heap regardless the
number of backups are specified?

Sent from: http://apache-ignite-users.70518.x6.nabble.com/

Best regards,
Andrey V. Mashenkov

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