Andrey, thanks for pointing this out. I think this is a serious usability issue. Do I understand correctly that we currently simply ignore a change in backup count if the persistence is enabled? If yes, we should fix it ASAP. I would also add a check for other configuration properties, like the affinity function, cache name, etc...
D. On Fri, Oct 27, 2017 at 7:46 AM, Andrey Mashenkov < andrey.mashen...@gmail.com> wrote: > Crossposting to dev. > > Igniters, > > 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 > finished). > 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.kat...@maxpoint.com> > Date: Thu, Oct 19, 2017 at 9:29 PM > Subject: Re: Query performance against table with/out backup > To: u...@ignite.apache.org > > > Here, I am trying to ascertain that I set backup == 2 properly as I > mentioned > 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 > visor. > > 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 >
