gaozhangmin opened a new issue, #3973: URL: https://github.com/apache/bookkeeper/issues/3973
In a typical bookkeeper deployment, SSD disks are used to store Journal log data, while HDD disks are used to store Ledger data. Data writes are initially stored in memory and then asynchronously flushed to the HDD disk in the background. However, due to memory limitations, the amount of data that can be cached is restricted. Consequently, requests for historical data ultimately rely on the HDD disk, which becomes a bottleneck for the entire Bookkeeper cluster. Moreover, during data recovery processes following node failures, a substantial amount of historical data needs to be read from the HDD disk, leading to the disk's I/O utilization reaching maximum capacity and resulting in significant read request delays or failures. To address these challenges, a new architecture is proposed: the introduction of a disk cache between the memory cache and the HDD disk, utilizing an SSD disk as an intermediary medium to significantly extend data caching duration. The data flow is as follows: journal -> write cache -> SSD cache -> HDD disk. The SSD disk cache functions as a regular LedgerStorage layer and is compatible with all existing LedgerStorage implementations. The following outlines the process: 1. Data eviction from the disk cache to the Ledger data disk occurs on a per-log file basis. 2. A new configuration parameter, diskCacheRetentionTime, is added to set the duration for which hot data is retained. Files with write timestamps older than the retention time will be evicted to the Ledger data disk. 3. A new configuration parameter, diskCacheThreshold, is added. If the disk cache utilization exceeds the threshold, the eviction process is accelerated. Data is evicted to the Ledger data disk based on the order of file write time until the disk space recovers above the threshold. 4. A new thread, ColdStorageArchiveThread, is introduced to periodically evict data from the disk cache to the Ledger data disk. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
