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Architecture - User Level OSS
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Summary Requirements
| io_cli_fail | if a Lustre client fails, and the OSS has partially executed an IO operation, it leaves the server file system in a reasonable state. |
| io_oss_fail | if an OSS fails, a client will retry to complete partial IO operations and they will complete as if the OSS had not failed |
| io_no_copy | for large IO transfers there will be no copy of data pages as is common in read/write system call implementation. |
| io_double_failure | If the OSS and the client fail, allowing 0's in the file due to truncation is certainly permitted, even the possibility of bad data like in ext3 write back mode is probably acceptable. |
| io_llog_refinement | Ideally with LAID llogging, a more complex method can be introduced that can undo the damage in the double failure case |
