一 buffers, cached
buffers: used to cache metadata and pages, which can be understood as system cache
cached: is used to cache files, which can be understood as data block cache
2 Manually trigger the cached recycling method
a) clean pagecache (page cache)
# echo 1 > /proc/sys/vm/drop_caches 或者 # sysctl -w vm.drop_caches=1
b) clean up dentries (directory cache) and inodes
# echo 2 > /proc/sys/vm/drop_caches 或者 # sysctl -w vm.drop_caches=2
c) Clean up pagecache, dentries and inodes
# echo 3 > /proc/sys/vm/drop_caches 或者 # sysctl -w vm.drop_caches=3
Others: Due to active intervention to clean up cached, the dirty data of the file system will be written back, and the usage rate of engine io increases