is it possible to separately store l1 and l2 or l3 blob in different disks?

[kolinfluence]

would like to store l1 in the fastest disk possible and l2 and l3 is slower disks. is this possible? also wal stored separately too

[royguo]

@kolinfluence Take a look at these options:

  // A list of paths where SST files can be put into, with its target size.
  // Newer data is placed into paths specified earlier in the vector while
  // older data gradually moves to paths specified later in the vector.
  //
  // For example, you have a flash device with 10GB allocated for the DB,
  // as well as a hard drive of 2TB, you should config it to be:
  //   [{"/flash_path", 10GB}, {"/hard_drive", 2TB}]
  //
  // The system will try to guarantee data under each path is close to but
  // not larger than the target size. But current and future file sizes used
  // by determining where to place a file are based on best-effort estimation,
  // which means there is a chance that the actual size under the directory
  // is slightly more than target size under some workloads. User should give
  // some buffer room for those cases.
  //
  // If none of the paths has sufficient room to place a file, the file will
  // be placed to the last path anyway, despite to the target size.
  //
  // Placing newer data to earlier paths is also best-efforts. User should
  // expect user files to be placed in higher levels in some extreme cases.
  //
  // If left empty, only one path will be used, which is db_name passed when
  // opening the DB.
  // Default: empty
  std::vector<DbPath> db_paths;

  // This specifies the info LOG dir.
  // If it is empty, the log files will be in the same dir as data.
  // If it is non empty, the log files will be in the specified dir,
  // and the db data dir's absolute path will be used as the log file
  // name's prefix.
  std::string db_log_dir = "";

  // This specifies the absolute dir path for write-ahead logs (WAL).
  // If it is empty, the log files will be in the same dir as data,
  //   dbname is used as the data dir by default
  // If it is non empty, the log files will be in kept the specified dir.
  // When destroying the db,
  //   all log files in wal_dir and the dir itself is deleted
  std::string wal_dir = "";