Hi, I am trying to understand in details how much metadata is being cached in ARC and L2ARC for my workload. 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? Is there any way to calculate how much metadata a filesystem is using? In other words, if I want to cache all the metadata for my entire filesystem, how much space will that take? 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 -- This message posted from opensolaris.org