John wrote: > Hi, > > I am trying to understand in details what is the ratio between metadata and > data in ARC and L2ARC for my system. > Looking at 'kstat -n arcstats', I see: > > ARC Current Size: 19217 MB (size=19,644,754,928) > ARC Metadata Size: 112MB (hdr_size=117,896,760) > > I am trying to understand what l2_hdr_size means? Is this the metadata stored > in ARC used to reference L2ARC content? or is it metadata stored in L2ARC? If > the former, where the size of the metadata located in ARC to reference L2ARC > content? > > In general, I am trying to decide if my L2ARC should only store metadata or > metadata+data. My workload is very random and *I think* does not benefit from > caching. > > Here is the full output: > kstat -n arcstats > module: zfs instance: 0 > name: arcstats class: misc > c 19644817124 > c_max 24686542848 > c_min 3085817856 > crtime 139.366765387 > data_size 18459594240 > deleted 111310878 > demand_data_hits 56990788 > demand_data_misses 631678 > demand_metadata_hits 391511844 > demand_metadata_misses 23702633 > evict_skip 8773774 > hash_chain_max 16 > hash_chains 362312 > hash_collisions 142969185 > hash_elements 1257608 > hash_elements_max 1368567 > hdr_size 117896760 > hits 505821153 > l2_abort_lowmem 165 > l2_cksum_bad 0 > l2_evict_lock_retry 2219 > l2_evict_reading 0 > l2_feeds 1407223 > l2_free_on_write 5785987 > l2_hdr_size 116243656 > l2_hits 16984766 > l2_io_error 0 > l2_misses 8707048 > l2_read_bytes 93748148736 > l2_rw_clash 972 > l2_size 63115001856 > l2_write_bytes 5882913534976 > l2_writes_done 958486 > l2_writes_error 0 > l2_writes_hdr_miss 3397 > l2_writes_sent 958486 > memory_throttle_count 108 > mfu_ghost_hits 15023125 > mfu_hits 422352855 > misses 25693849 > mru_ghost_hits 2680252 > mru_hits 29672107 > mutex_miss 525565 > other_size 961128416 > p 18417019126 > prefetch_data_hits 925997 > prefetch_data_misses 440681 > prefetch_metadata_hits 56392524 > prefetch_metadata_misses 918857 > recycle_miss 27494219 > size 19644754928 > snaptime 843583.792905623
Wrong sort of ARC (Architecture Review Council), you'll have more luck on zfs-discuss. -tim
