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https://issues.jboss.org/browse/ISPN-78?page=com.atlassian.jira.plugin.sy...
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Olaf Bergner commented on ISPN-78:
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Hi Gabriel,
it is my understanding that Reed-Solomon codes aide in detecting and correcting data
corruption. In our scenario this equates to repairing chunks that have somehow been
corrupted. I have thought about later implementing some means of doing so myself, so
thanks for the hint.
What I fail to see, though, is how this would help to address the problem of availability
in the face of node failures. If two nodes storing the same chunk are down that chunk and
thus the large object it belongs to are not available. Or would it be possible using RS
codes to reconstruct a missing chunk from the information contained in the other chunks?
Large object support
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Key: ISPN-78
URL:
https://issues.jboss.org/browse/ISPN-78
Project: Infinispan
Issue Type: Feature Request
Components: Core API
Reporter: Manik Surtani
Assignee: Olaf Bergner
Fix For: 5.1.0.BETA1, 5.1.0.Final
if each VM is allocated a 2GB heap and you have a 100 nodes in a grid with 1 redundant
copy for each key, you have a theoretical addressable heap of 100GB. But you are limited
by (half) the heap of a single VM per entry, since entries are stored whole.
E.g., cache.put(k, my2GBObject) will fail since you need at least 2GB for the object +
another 2GB for its serialized form.
This gets worse when you try cache.put(k, my10GBObject). This *should* be possible if we
have a theoretical 100GB heap.
Potential solutions here are to fragment large objects, and store each fragment under
separate keys. Another approach would be to directly stream objects to disk. etc. Needs
thought and design, possibly a separate API to prevent 'pollution" of the more
simplistic API. (JumboCache?)
Re: fragmenting, issues to overcome:
How many chunks to fragment into? Max size of each key could be configured, but how do
we determine the size of an Object? VM instrumentation? Or perhaps the JumboCache only
stores byte[]'s?
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