Hello David! Yes, I think that should be possible to implement. However, when a node fails there would be a massive backlog of rebalancing on just two nodes, and it might cause a problem on its own. Random placement guarantees that rebalancings are placed evenly in case of node failure
Regards, -- Ilya Kasnacheev 2018-05-17 19:11 GMT+03:00 David Harvey <dhar...@jobcase.com>: > We built a cluster with 8 nodes using Ignite persistence and 1 backup, and > had two nodes fail at different times, the first being storage did not get > mounted and ran out of space early, and the second an SSD failed. There > are some things that we could have done better, but this event brings up > the question of how backups are distributed. > > There are two approaches that have substantially different behavior on > double faults, and double faults are more likely at scale. > > 1) random placement of backup partitions relative to primary > 2) backup partitions have similar affinity to the primary partitions, > where in the extreme nodes are paired so that primaries on the node pair > have backups on the other node of the pair > > With a 64 node cluster, #2 would have 1/63th of the likelihood of data > loss when 2 nodes fail vs #1. > > I'm guessing that ignite ships with #1, but we could provide our own > affinity function which would accomplish #2 if we chose? > > > > > *Disclaimer* > > The information contained in this communication from the sender is > confidential. It is intended solely for use by the recipient and others > authorized to receive it. If you are not the recipient, you are hereby > notified that any disclosure, copying, distribution or taking action in > relation of the contents of this information is strictly prohibited and may > be unlawful. > > This email has been scanned for viruses and malware, and may have been > automatically archived by *Mimecast Ltd*, an innovator in Software as a > Service (SaaS) for business. Providing a *safer* and *more useful* place > for your human generated data. Specializing in; Security, archiving and > compliance. To find out more Click Here > <http://www.mimecast.com/products/>. >
