[GitHub] [incubator-kvrocks] xiaobiaozhao commented on issue #918: support Multi-disk(Multi-path)

[GitBox <gi...@apache.org>]

xiaobiaozhao commented on issue #918:
URL: https://github.com/apache/incubator-kvrocks/issues/918#issuecomment-1257314367

   
   
   
   > > Hi @xiaobiaozhao, I have two questions:
   > > 
   > > 1. Why can multiple disks improve performance? Multiple paths do not seem to work in parallel.
   > > 2. How do we judge hot and cold data in kvrocks? Rocksdb simply determines where to place the SST based on when the SST was generated.
   > 
   > According to the description of the configuration, the lower level SST will be stored in the front of the `db_paths`. So we can arrange the `db_paths` according to the speed of the storage medium, and put the low-level SST in the faster storage medium, for example, put the SSD in the first of the `db_paths` to storage the low-level SST.
   > 
   > In fact, the level at which `SST` is located represents the hot and coldness of the data. Because rocksdb uses the LSM tree, it will naturally merge cold data to a higher level.
   > 
   > So if this feature is used, rocksdb can help us store cold data in slower storage media such as mechanical hard drives, and store hot data in faster storage media such as SSD.
   
   Yes，In my test demo，rocksdb use first & last of the `dp_paths` config only. 


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