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https://issues.apache.org/jira/browse/SOLR-15051?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17258633#comment-17258633
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Jason Gerlowski commented on SOLR-15051:
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bq. In Solr we have a "BackupRepository" abstraction ... but it might as well
be called something like "RemoteStorageRepository" that is not just usable for
Backup/restore but also as a backing abstraction for shared storage generally.
That sounds reasonable to me, both in terms of naming and in terms of expanding
the intended purpose of that interface.
(In fact, this is very related to some of the discussions I'm trying to start
in SIP-12, a part of which aims at better support for backup/restore to blob
stores. I've been wondering how we might be able to align our efforts. At
first glance, generalizing BackupRepository seems like it'd be a good way to
push in the same direction without stepping on toes. Though I need to think
about it more to be more sure.)
> Shared storage -- BlobDirectory (de-duping)
> -------------------------------------------
>
> Key: SOLR-15051
> URL: https://issues.apache.org/jira/browse/SOLR-15051
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Reporter: David Smiley
> Assignee: David Smiley
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> This proposal is a way to accomplish shared storage in SolrCloud with a few
> key characteristics: (A) using a Directory implementation, (B) delegates to a
> backing local file Directory as a kind of read/write cache (C) replicas have
> their own "space", (D) , de-duplication across replicas via reference
> counting, (E) uses ZK but separately from SolrCloud stuff.
> The Directory abstraction is a good one, and helps isolate shared storage
> from the rest of SolrCloud that doesn't care. Using a backing normal file
> Directory is faster for reads and is simpler than Solr's HDFSDirectory's
> BlockCache. Replicas having their own space solves the problem of multiple
> writers (e.g. of the same shard) trying to own and write to the same space,
> and it implies that any of Solr's replica types can be used along with what
> goes along with them like peer-to-peer replication (sometimes faster/cheaper
> than pulling from shared storage). A de-duplication feature solves needless
> duplication of files across replicas and from parent shards (i.e. from shard
> splitting). The de-duplication feature requires a place to cache directory
> listings so that they can be shared across replicas and atomically updated;
> this is handled via ZooKeeper. Finally, some sort of Solr daemon /
> auto-scaling code should be added to implement "autoAddReplicas", especially
> to provide for a scenario where the leader is gone and can't be replicated
> from directly but we can access shared storage.
> For more about shared storage concepts, consider looking at the description
> in SOLR-13101 and the linked Google Doc.
> *[PROPOSAL
> DOC|https://docs.google.com/document/d/1kjQPK80sLiZJyRjek_Edhokfc5q9S3ISvFRM2_YeL8M/edit?usp=sharing]*
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