[zfs-discuss] High performance SAN with ZoL

Andreas Bauer Andreas.Bauer at voltage.de
Sat Jan 2 10:44:51 EST 2016


Am 02.01.2016 um 16:35 schrieb Andreas Bauer:

> No usage of the L2ARC at all. In production, I see at least some usage.
> 
> What is going wrong here? The L2ARC has almost all of the data, but gets
> no use. Instead, the data is taken from the hard disks.
> 
> ZFS 0.6.5.2-2 on Debian 8.2 with 4.3.3-2 kernel from testing. Same issue
> was before with 3.16 Jessie Kernel and 4.2 Backports Kernel.

Here is the contents of /proc/spl/kstat/zfs/arcstats

name                            type data
hits                            4    262855940
misses                          4    213370194
demand_data_hits                4    248452916
demand_data_misses              4    4694710
demand_metadata_hits            4    6324388
demand_metadata_misses          4    446781
prefetch_data_hits              4    4777982
prefetch_data_misses            4    206565538
prefetch_metadata_hits          4    3300654
prefetch_metadata_misses        4    1663165
mru_hits                        4    218272699
mru_ghost_hits                  4    78838
mfu_hits                        4    36515573
mfu_ghost_hits                  4    40062
deleted                         4    227253497
mutex_miss                      4    3117
evict_skip                      4    8060235
evict_not_enough                4    7
evict_l2_cached                 4    2446972751360
evict_l2_eligible               4    45414945792
evict_l2_ineligible             4    3408943298048
evict_l2_skip                   4    0
hash_elements                   4    16604387
hash_elements_max               4    16715193
hash_collisions                 4    103581049
hash_chains                     4    4369706
hash_chain_max                  4    11
p                               4    63328496640
c                               4    67550396416
c_min                           4    33554432
c_max                           4    67550396416
size                            4    67502499104
hdr_size                        4    277559384
data_size                       4    64397115392
metadata_size                   4    1008088576
other_size                      4    164053984
anon_size                       4    147456
anon_evictable_data             4    0
anon_evictable_metadata         4    0
mru_size                        4    61296995840
mru_evictable_data              4    60486057984
mru_evictable_metadata          4    698584576
mru_ghost_size                  4    2145230848
mru_ghost_evictable_data        4    76808192
mru_ghost_evictable_metadata    4    2068422656
mfu_size                        4    4108060672
mfu_evictable_data              4    3910926336
mfu_evictable_metadata          4    197117952
mfu_ghost_size                  4    399872
mfu_ghost_evictable_data        4    180224
mfu_ghost_evictable_metadata    4    219648
l2_hits                         4    237868
l2_misses                       4    213132275
l2_feeds                        4    96884
l2_rw_clash                     4    291
l2_read_bytes                   4    3792304640
l2_write_bytes                  4    1751175495680
l2_writes_sent                  4    45262
l2_writes_done                  4    45262
l2_writes_error                 4    0
l2_writes_lock_retry            4    122
l2_evict_lock_retry             4    2
l2_evict_reading                4    0
l2_evict_l1cached               4    17
l2_free_on_write                4    21958
l2_cdata_free_on_write          4    2622
l2_abort_lowmem                 4    0
l2_cksum_bad                    4    0
l2_io_error                     4    0
l2_size                         4    2150731734016
l2_asize                        4    1487714184704
l2_hdr_size                     4    1655681768
l2_compress_successes           4    9110483
l2_compress_zeros               4    0
l2_compress_failures            4    10273681
memory_throttle_count           4    0
duplicate_buffers               4    0
duplicate_buffers_size          4    0
duplicate_reads                 4    0
memory_direct_count             4    0
memory_indirect_count           4    0
arc_no_grow                     4    0
arc_tempreserve                 4    0
arc_loaned_bytes                4    0
arc_prune                       4    0
arc_meta_used                   4    3105383712
arc_meta_limit                  4    50662797312
arc_meta_max                    4    4352868616
arc_meta_min                    4    16777216
arc_need_free                   4    0
arc_sys_free                    4    2110947328



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