我一直在一台装有 Ubuntu 12.10、32GB RAM（非 ECC，生产系统将具有 ECC）和一个 2x2TB Linux 管理的 RAID1（将移至 RAIDZ1 用于生产）的机器上试验 ZFS。我刚刚在 2TB soft-RAID1 设备上创建了 tank，启用了压缩和重复数据删除并存储了几个 100GB 的数据。
我得到了大约 3.5 倍的重复数据删除率（这对我的数据真的很有意义，这就是我想使用它的原因），但根本没有可用内存，系统变得无法使用。重新启动系统，一切正常，然后我写了几GB的数据，同样的事情。
然后我将 zfs_arc_max 设置为 12GB（因为显然我不是唯一一个内存消耗失控的人），这使系统免于无响应，但是写入几 GB 使内存限制达到最大值并且写入坦克变得非常缓慢，基本无法使用。
我知道重复数据删除需要 RAM，但据我所知，这
DDT-sha256-zap-duplicate: 615271 entries, size 463 on disk, 149 in core
DDT-sha256-zap-unique: 846070 entries, size 494 on disk, 159 in core
DDT histogram (aggregated over all DDTs):
bucket allocated referenced
______ ______________________________ ______________________________
refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE
------ ------ ----- ----- ----- ------ ----- ----- -----
1 826K 83.5G 51.7G 52.9G 826K 83.5G 51.7G 52.9G
2 363K 34.6G 17.8G 18.5G 869K 81.9G 41.3G 43.0G
4 138K 14.1G 8.89G 9.11G 654K 66.4G 41.0G 42.1G
8 49.0K 3.94G 2.25G 2.34G 580K 44.3G 25.3G 26.4G
16 37.2K 3.96G 3.06G 3.10G 865K 90.1G 69.9G 70.8G
32 9.81K 854M 471M 488M 464K 40.5G 21.9G 22.7G
64 1.84K 160M 80.8M 85.1M 148K 11.8G 5.99G 6.33G
128 1.13K 60.4M 24.7M 27.7M 218K 11.2G 4.70G 5.26G
256 545 52.9M 30.9M 32.1M 169K 15.5G 9.00G 9.36G
512 120 7.17M 4.19M 4.51M 84.5K 5.09G 2.96G 3.18G
1K 368 40.0M 19.0M 19.7M 480K 52.2G 24.8G 25.7G
2K 16 401K 23K 76K 46.4K 1.31G 73.5M 226M
4K 8 5K 4K 32K 39.9K 24.6M 20.0M 160M
Total 1.39M 141G 84.3G 86.6G 5.32M 504G 299G 308G
意味着该表应该只占用大约 90MB 的内存，所以我不明白发生了什么。我在没有重复数据删除的相同服务器上有相同的设置，而且那个似乎工作正常......
我真的很感激任何帮助（除了“禁用重复数据删除”，因为它确实对我的数据有意义；))！更多数据：
tank type filesystem -
tank creation Thu Jan 16 13:17 2014 -
tank used 342G -
tank available 1.67T -
tank referenced 341G -
tank compressratio 1.64x -
tank mounted yes -
tank quota none default
tank reservation none default
tank recordsize 128K default
tank mountpoint / tank default
tank sharenfs off default
tank checksum on default
tank compression lzjb local
tank atime off local
tank devices on default
tank exec on default
tank setuid on default
tank readonly off default
tank zoned off default
tank snapdir hidden default
tank aclinherit restricted default
tank canmount on default
tank xattr sa local
tank copies 1 default
tank version 5 -
tank utf8only off -
tank normalization none -
tank casesensitivity sensitive -
tank vscan off default
tank nbmand off default
tank sharesmb off default
tank refquota none default
tank refreservation none default
tank primarycache all default
tank secondarycache all default
tank usedbysnapshots 36.9M -
tank usedbydataset 341G -
tank usedbychildren 702M -
tank usedbyrefreservation 0 -
tank logbias latency default
tank dedup on local
tank mlslabel none default
tank sync standard default
tank refcompressratio 1.64x -
tank written 308K -
tank snapdev hidden default
更新了更多数据。
好的，所以我进行了另一个测试 - 重新启动服务器，安装卷等：
total used free shared buffers cached
Mem: 32138 457 31680 0 19 66
-/+ buffers/cache: 372 31766
Swap: 7812 0 7812
和 arcstats
4 1 0x01 84 4032 7898070146 560489175172
name type data
hits 4 1059
misses 4 185
demand_data_hits 4 0
demand_data_misses 4 0
demand_metadata_hits 4 971
demand_metadata_misses 4 49
prefetch_data_hits 4 0
prefetch_data_misses 4 7
prefetch_metadata_hits 4 88
prefetch_metadata_misses 4 129
mru_hits 4 476
mru_ghost_hits 4 0
mfu_hits 4 495
mfu_ghost_hits 4 0
deleted 4 9
recycle_miss 4 0
mutex_miss 4 0
evict_skip 4 0
evict_l2_cached 4 0
evict_l2_eligible 4 0
evict_l2_ineligible 4 2048
hash_elements 4 176
hash_elements_max 4 176
hash_collisions 4 0
hash_chains 4 0
hash_chain_max 4 0
p 4 6442450944
c 4 12884901888
c_min 4 1610612736
c_max 4 12884901888
size 4 1704536
hdr_size 4 101424
data_size 4 1448960
other_size 4 154152
anon_size 4 16384
anon_evict_data 4 0
anon_evict_metadata 4 0
mru_size 4 1231872
mru_evict_data 4 206336
mru_evict_metadata 4 849408
mru_ghost_size 4 0
mru_ghost_evict_data 4 0
mru_ghost_evict_metadata 4 0
mfu_size 4 200704
mfu_evict_data 4 0
mfu_evict_metadata 4 4096
mfu_ghost_size 4 16384
mfu_ghost_evict_data 4 0
mfu_ghost_evict_metadata 4 16384
l2_hits 4 0
l2_misses 4 0
l2_feeds 4 0
l2_rw_clash 4 0
l2_read_bytes 4 0
l2_write_bytes 4 0
l2_writes_sent 4 0
l2_writes_done 4 0
l2_writes_error 4 0
l2_writes_hdr_miss 4 0
l2_evict_lock_retry 4 0
l2_evict_reading 4 0
l2_free_on_write 4 0
l2_abort_lowmem 4 0
l2_cksum_bad 4 0
l2_io_error 4 0
l2_size 4 0
l2_asize 4 0
l2_hdr_size 4 0
l2_compress_successes 4 0
l2_compress_zeros 4 0
l2_compress_failures 4 0
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 1498200
arc_meta_limit 4 3221225472
arc_meta_max 4 1449144
玩了一会儿，直到 ARC 达到 vfs_arc_max (12GB)：
4 1 0x01 84 4032 7898070146 1406380500230
name type data
hits 4 7338384
misses 4 117090
demand_data_hits 4 4841648
demand_data_misses 4 10072
demand_metadata_hits 4 2423640
demand_metadata_misses 4 35334
prefetch_data_hits 4 37879
prefetch_data_misses 4 65420
prefetch_metadata_hits 4 35217
prefetch_metadata_misses 4 6264
mru_hits 4 2672085
mru_ghost_hits 4 301
mfu_hits 4 4615778
mfu_ghost_hits 4 1183
deleted 4 9
recycle_miss 4 1022
mutex_miss 4 17
evict_skip 4 2
evict_l2_cached 4 0
evict_l2_eligible 4 1977338368
evict_l2_ineligible 4 751589376
hash_elements 4 166822
hash_elements_max 4 166828
hash_collisions 4 59458
hash_chains 4 21504
hash_chain_max 4 4
p 4 55022931
c 4 12652319216
c_min 4 1610612736
c_max 4 12884901888
size 4 12327222416
hdr_size 4 55933440
data_size 4 12149027328
other_size 4 122261648
anon_size 4 1056256
anon_evict_data 4 0
anon_evict_metadata 4 0
mru_size 4 6481734656
mru_evict_data 4 6220393984
mru_evict_metadata 4 188646912
mru_ghost_size 4 1902724096
mru_ghost_evict_data 4 1871710720
mru_ghost_evict_metadata 4 31013376
mfu_size 4 5666236416
mfu_evict_data 4 5643978240
mfu_evict_metadata 4 16081408
mfu_ghost_size 4 708022272
mfu_ghost_evict_data 4 680676352
mfu_ghost_evict_metadata 4 27345920
l2_hits 4 0
l2_misses 4 0
l2_feeds 4 0
l2_rw_clash 4 0
l2_read_bytes 4 0
l2_write_bytes 4 0
l2_writes_sent 4 0
l2_writes_done 4 0
l2_writes_error 4 0
l2_writes_hdr_miss 4 0
l2_evict_lock_retry 4 0
l2_evict_reading 4 0
l2_free_on_write 4 0
l2_abort_lowmem 4 0
l2_cksum_bad 4 0
l2_io_error 4 0
l2_size 4 0
l2_asize 4 0
l2_hdr_size 4 0
l2_compress_successes 4 0
l2_compress_zeros 4 0
l2_compress_failures 4 0
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 1947
arc_no_grow 4 0
arc_tempreserve 4 0
arc_loaned_bytes 4 0
arc_prune 4 0
arc_meta_used 4 462466704
arc_meta_limit 4 3221225472
arc_meta_max 4 465357280
和 free -m 显示了预期的内容，缓冲区/缓存和第一行同意使用/免费。但是，多玩一些会导致系统变得异常缓慢（复制 1GB 的时间）和
total used free shared buffers cached
Mem: 32138 31923 215 0 6 15442
-/+ buffers/cache: 16473 15665
Swap: 7812 0 7812
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 1 308 3774708 27204 9464052 0 0 386 271 72 348 1 2 83 15
卸载 ZFS 卷并卸载内核模块会释放所有内存......所以对我来说，它真的看起来像是某种内存泄漏：设置了 zfs_arc_max，arcstats 说这个限制被观察到（见下文），但 ZFS 不知何故继续吃掉内存。呼...
time read miss miss% dmis dm% pmis pm% mmis mm% arcsz c
14:08:08 0 0 0 0 0 0 0 0 0 9.8G 10G