Hi Pavel,
Well based upon documentation of
ClusterNodeAttributeAffinityBackupFilter.java class. It says "This
implementation will discard backups rather than place multiple on the same
set of nodes. This avoids trying to cram more data onto remaining nodes
when some have failed." and i have verified the same by running a small
test with three node cluster (one assigned with node attribute as
AVAILABILITY_ZONE=ZONE1 and other two assigned node attribute
AVAILABILITY_ZONE=ZONE2) , Created a cache with 2 backups and using
ClusterNodeAttributeAffinityBackupFilter in RendezvousAffinityFunction as
below. After that added an entry into the cache and verified the nodes
count for both primary and backup using cache affinity function. It
returned 2 instead of 3.
ClusterNodeAttributeAffinityBackupFilter backupFilter = new
ClusterNodeAttributeAffinityBackupFilter("AVAILABILITY_ZONE");
RendezvousAffinityFunction rendezvousAffinityFunction = new
RendezvousAffinityFunction();
rendezvousAffinityFunction.setAffinityBackupFilter(backupFilter);
CacheConfiguration<String, String> cacheConfiguration = new
CacheConfiguration<>();
cacheConfiguration.setBackups(2);
cacheConfiguration.setAffinity(rendezvousAffinityFunction);
IgniteCache<String, String> cache = ignite.getOrCreateCache(cacheConfiguration);
cache.put("1","1");
Collection<ClusterNode> nodes =
((Ignite)cache.unwrap(Ignite.class)).affinity(cache.getName()).mapKeyToPrimaryAndBackups("1");
assertEquals(3, nodes.size()); //This fails even though i have three
nodes (1 with node attribute AVAILABILITY_ZONE="ZONE1" and other two
with node attribute AVAILABILITY_ZONE="ZONE2")
PS: I started three nodes with Custom cache
configuration IgniteConfiguration.setUserAttributes
Server Node1
=====================================
Map<String, String> userAttributes = new HashMap<>();
userAttributes.put("AVAILABILITY_ZONE", "ZONE1");
IgniteConfiguration cfg = new IgniteConfiguration();
cfg.setUserAttributes(userAttributes);
Ignition.start(cfg);
Server Node2
=====================================
Map<String, String> userAttributes = new HashMap<>();
userAttributes.put("AVAILABILITY_ZONE", "ZONE2");
IgniteConfiguration cfg = new IgniteConfiguration();
cfg.setUserAttributes(userAttributes);
Ignition.start(cfg);
Server Node3
=====================================
Map<String, String> userAttributes = new HashMap<>();
userAttributes.put("AVAILABILITY_ZONE", "ZONE2");
IgniteConfiguration cfg = new IgniteConfiguration();
cfg.setUserAttributes(userAttributes);
Ignition.start(cfg);
https://ignite.apache.org/releases/latest/javadoc/org/apache/ignite/cache/affinity/rendezvous/ClusterNodeAttributeAffinityBackupFilter.html
Thanks,
Amit Jolly
On Thu, Sep 19, 2024 at 12:51 AM Pavel Tupitsyn <ptupit...@apache.org>
wrote:
> Hi Amit,
>
> > if the backup count is let's say 2, Ignite won't create a second backup
> as there are not enough zones
> Not correct - Ignite will create backups anyway.
> - A backup is a copy of a partition on another node
> - With 2 backups every partition will have 3 copies (1 primary, 2 backup),
> all on different nodes (since you have 10 nodes)
> - Use ClusterNodeAttributeAffinityBackupFilter to ensure that at least one
> of the copies is in a different AZ
>
> And that is enough for 3 copies.
>
> On Thu, Sep 19, 2024 at 12:10 AM Amit Jolly <amit.jo...@gmail.com> wrote:
>
>> Hi Team
>>
>> We are planning to run 10 node Ignite clusters in AWS with 5 nodes each
>> into two availability zones. Using Kubernetes topologyspreadconstraints we
>> have made sure that no two Ignite pods are started on the same virtual
>> machine/node/host.
>>
>> I understand with ClusterNodeAttributeAffinityBackupFilter i can force
>> ignite to store the backup in a different zone if backup count is 1.
>>
>> But if the backup count is let's say 2, Ignite won't create a second
>> backup as there are not enough zones.
>>
>> My question is if i have backup count 2, How can I
>> use ClusterNodeAttributeAffinityBackupFilter or (custom
>> AffinityBackupFilter) to have at least one backup in each zone and another
>> backup anywhere else where available.
>>
>> I think in order to achieve what I am thinking somehow I
>> need currentTopologySnapshot
>> available in ClusterNodeAttributeAffinityBackupFilter or custom
>> AffinityBackupFilter
>>
>> Thanks,
>>
>> Amit Jolly
>>
>
