Mulugeta Mammo created IGNITE-6854:
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Summary: Enabling Persistent Memory for Ignite
Key: IGNITE-6854
URL: https://issues.apache.org/jira/browse/IGNITE-6854
Project: Ignite
Issue Type: New Feature
Security Level: Public (Viewable by anyone)
Affects Versions: 2.3
Reporter: Mulugeta Mammo
Fix For: 2.4
Ignite, when persistence mode is enabled, stores data and indexes on disk. To
minimize the latency of disks, several tuning options can be applied. Setting
the page size of a memory region to match the page size of the underlying
storage, using a separate disk for the WAL, and using production-level SSDs are
just a few of them [
https://apacheignite.readme.io/docs/durable-memory-tuning#section-native-persistence-related-tuning
].
A persistent memory store with low latency and high capacity offers a viable
alternative to disks. In light of this, we are proposing to make use of our Low
Level Persistent Library (LLPL), https://github.com/pmem/pcj/tree/master/LLPL,
to offer a persistent memory storage for Ignite.
At this point, we envision two distinct implementation options:
# Data and indexes will continue to be stored in the off-heap memory but the
disk will be replaced by a persistent memory. Since persistence memory in this
option is not a file system, the logic currently offered by WAL file and the
partition files would have to be implemented from scratch.
#
# In this option, we eliminate the current check-point process and the WAL
file. We will use a memory region defined by LLPL to store data and indexes.
There will be no off-heap memory. DRAM will be exclusively used to store hot
cache entries just like the on-heap cache is in the current implementation.
#
In both cases, there are more details and subtleties that have to handled –
e.g. the atomic and transactional guarantees offered. More clarifications will
be offered as we go along.
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