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Ignite with enabled persistence uses following folder structure:
| 2.3+ | Older versions (2.1 & 2.2) | ||
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The Pst-subfolder name is same for all storage folders. A name is selected on start, may be based on node consistentId. |
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Subfolders Generation
The subfolder name is generated on start. By default new style naming is used, for example node00-e819f611-3fb9-4dbe-a3aa-1f6de4af5d02
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Collection of pages (GridCacheDatabaseSharedManager.Checkpoint#cpPages) is a snapshot of dirty pages at checkpoint start. This collection allows writing pages which were changed since the last checkpoint.
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When the checkpoint process starts, pages marked for checkpoint are no longer marked as dirty ones in metrics. |
Checkpoint Pool
In parallel with the process of writing pages to disk, some thread may need to update data in the page being written (or scheduled to being written).
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- exponential backoff (start with ultra-short park, every next park will be <factor> times longer)
- and speed-based (collect the history of disk write speed measurements, extrapolate it to calculate "ideal" speed, and bound threads that generate dirty pages with that "ideal" speed). There are three main approaches:
- Exponential backoff is used if over 2/3 of the checkpoint buffer is used up. If it is enabled, other throttling strategies are not used.
- Clean pages protection is used if there are 0 checkpoint pages. It is used to protect pages at the start of the end of the checkpointing process.
- Throttling is based on a comparison of the speed of checkpointing and dirty pages creation. Uses the speed of checkpointing at +10% as the throttling limit.
Ignite node chooses one of them adaptively.
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