Exnode specification: Difference between revisions
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[[Example L-Store exnode xml file]] | [[Example L-Store exnode xml file]] | ||
== Schema == | |||
The exnode xml is fairly unstructured and the functionality of a schema is minimal. | |||
[[Simplified xml file]] | |||
*(removed xmlns to view structure more clearly) | |||
[[Simple schema]] | |||
*The schema shows that only the element "mapping" has required elements. | |||
*The element metadata's use of attributes is completely open. | |||
*The only re-used type is the IBP_capability (read,write,manage) | |||
== Erasure codings == | == Erasure codings == | ||
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**simple offsets and lengths | **simple offsets and lengths | ||
**non-blocked (vector) reads | **non-blocked (vector) reads | ||
Revision as of 21:54, 16 January 2008
The exnode specification is implied by current usage in L-Store and LoRS.
Example L-Store exnode xml file
Schema
The exnode xml is fairly unstructured and the functionality of a schema is minimal.
- (removed xmlns to view structure more clearly)
- The schema shows that only the element "mapping" has required elements.
- The element metadata's use of attributes is completely open.
- The only re-used type is the IBP_capability (read,write,manage)
Erasure codings
- L-Store writes extra erasure allocations for allocation recovery.
- erasure allocations are also stored in the exnode file
- erasure allocations are only useful to the data-management area and not the data-client
- erasure allocations constitute an extension of the base (LoRS) exnode concept (or schema)
- L-Store can write a LoRS compatible exnode file that excludes the erasure allocations.
- LoRS compatible (the base schema)
- LoRS does not have access to L-Store's capability to recover an allocation
- The L-Store data-client (Lstcp) has no allocation recovery capability.
- data recovery, data warming, etc all data-management tasks, not data-client task.
Data client API & interfaces
- command line tools for file management
- list files, create directories, etc
- LoRS API
- uses the base exnode schema (LoRS)
- reads local exnode files
- talks to LoDN with a combined http:/LoDN protocol
- C/C++ Posix and posix-like API
- Lstcp API (not developed yet)
- does not use exnodes
- talks to L-Server with the L-Store protocol
- typical C/C++ API needs (proposed)
- simple offsets and lengths
- non-blocked (vector) reads