Ive been very happy with my FN setup (which is large). It does quite a bit of NFS (vmware so is sync) and SMB , both over 10gbit , every day.
No Jails nor FN hosted VMs (no bhyve), nor any plugins.
The full specs are in my sig. I dont use a L2ARC, but do have a single optane 280gb as SLOG.
Build FreeNAS-11.2-U5
Platform Intel(R) Xeon(R) CPU E5-2637 v2 @ 3.50GHz
Memory 262067MB
System Time Mon, 10 Aug 2020 16:21:44 -0500
Uptime 4:21PM up 312 days, 12:12, 5 users
Load Average 1.60, 1.67, 1.73
(i have been testing 11.3 extensively (on a separate physical box, im not ready to upgrade yet)
My 2x questions are: with 256gb of ram (ecc d3)
1- should i consider setting a static size for my ARC (ie a ARC reservation for metadata) ?
(i assume NO, but the idea is coming from these great threads ive read though , where the author also has 256gb, and seems to be in a similar scenario as me;
www.ixsystems.com
and
www.ixsystems.com
2- from the attached arc_summary.py output below, which entries stand out to you? (you being those very knowledgeable, and generous, users and admins on this forum)
For me:
ARC Size: 71.58% 177.88 GiB
Actual Hit Ratio: 94.07% 670.64b
- tells me FN/FreeBSD/ZFS is correctly allocating a large part of my 256gb to ARC (but should the 177 GB be higher? as i never will be running any FN "extras/bhyve")
- tells me ZFS , on average, 94 out of 100 times is able to pull the metadata it needs from the 177 GB Ram, as opposed to pulling it from my slow, HDDs.
(see image of hit ratio and Size over time- im also using the Remote Graphite Server" FN setting so i do have access to just about all of the arc_summary.py stats vs time, as well)
No Jails nor FN hosted VMs (no bhyve), nor any plugins.
The full specs are in my sig. I dont use a L2ARC, but do have a single optane 280gb as SLOG.
Build FreeNAS-11.2-U5
Platform Intel(R) Xeon(R) CPU E5-2637 v2 @ 3.50GHz
Memory 262067MB
System Time Mon, 10 Aug 2020 16:21:44 -0500
Uptime 4:21PM up 312 days, 12:12, 5 users
Load Average 1.60, 1.67, 1.73
(i have been testing 11.3 extensively (on a separate physical box, im not ready to upgrade yet)
My 2x questions are: with 256gb of ram (ecc d3)
1- should i consider setting a static size for my ARC (ie a ARC reservation for metadata) ?
(i assume NO, but the idea is coming from these great threads ive read though , where the author also has 256gb, and seems to be in a similar scenario as me;
Ways to leverage Optane in 12.0? (given 4k speed+latency, could Metadata+SLOG share devices, and is L2ARC less useful)
So for this question, I need to give a bit of background. BACKGROUND: MY SYSTEM UNDER 11.3: My pool data is very large, very dedupable files (20TB of VMs), to the point that the extra hardware for dedup was worth it to save HDD costs (3.5 x dedup, I'm saving about 200TB of SAS3 raw disk cost...

SLOG benchmarking and finding the best SLOG
What block size is used for servicing VMs over NFS? Trying to understand what size is most important.

2- from the attached arc_summary.py output below, which entries stand out to you? (you being those very knowledgeable, and generous, users and admins on this forum)
For me:
ARC Size: 71.58% 177.88 GiB
Actual Hit Ratio: 94.07% 670.64b
- tells me FN/FreeBSD/ZFS is correctly allocating a large part of my 256gb to ARC (but should the 177 GB be higher? as i never will be running any FN "extras/bhyve")
- tells me ZFS , on average, 94 out of 100 times is able to pull the metadata it needs from the 177 GB Ram, as opposed to pulling it from my slow, HDDs.
(see image of hit ratio and Size over time- im also using the Remote Graphite Server" FN setting so i do have access to just about all of the arc_summary.py stats vs time, as well)
Code:
System Memory: 0.01% 13.95 MiB Active, 0.56% 1.40 GiB Inact 95.96% 239.43 GiB Wired, 0.00% 0 Bytes Cache 2.33% 5.82 GiB Free, 1.14% 2.85 GiB Gap Real Installed: 256.00 GiB Real Available: 99.97% 255.93 GiB Real Managed: 97.49% 249.51 GiB Logical Total: 256.00 GiB Logical Used: 97.18% 248.78 GiB Logical Free: 2.82% 7.22 GiB Kernel Memory: 3.67 GiB Data: 98.87% 3.63 GiB Text: 1.13% 42.54 MiB Kernel Memory Map: 249.51 GiB Size: 6.39% 15.95 GiB Free: 93.61% 233.56 GiB Page: 1 ------------------------------------------------------------------------ ARC Summary: (HEALTHY) Storage pool Version: 5000 Filesystem Version: 5 Memory Throttle Count: 0 ARC Misc: Deleted: 11.87b Mutex Misses: 11.02m Evict Skips: 11.02m ARC Size: 71.58% 177.88 GiB Target Size: (Adaptive) 71.48% 177.63 GiB Min Size (Hard Limit): 12.50% 31.06 GiB Max Size (High Water): 8:1 248.51 GiB ARC Size Breakdown: Recently Used Cache Size: 90.44% 160.88 GiB Frequently Used Cache Size: 9.56% 17.00 GiB ARC Hash Breakdown: Elements Max: 9.81m Elements Current: 80.97% 7.94m Collisions: 4.76b Chain Max: 8 Chains: 804.95k Page: 2 ------------------------------------------------------------------------ ARC Total accesses: 712.94b Cache Hit Ratio: 94.30% 672.31b Cache Miss Ratio: 5.70% 40.63b Actual Hit Ratio: 94.07% 670.64b Data Demand Efficiency: 54.72% 39.05b Data Prefetch Efficiency: 20.94% 8.17b CACHE HITS BY CACHE LIST: Anonymously Used: 0.20% 1.37b Most Recently Used: 3.95% 26.58b Most Frequently Used: 95.80% 644.06b Most Recently Used Ghost: 0.01% 72.13m Most Frequently Used Ghost: 0.03% 224.49m CACHE HITS BY DATA TYPE: Demand Data: 3.18% 21.37b Prefetch Data: 0.25% 1.71b Demand Metadata: 96.54% 649.06b Prefetch Metadata: 0.03% 171.82m CACHE MISSES BY DATA TYPE: Demand Data: 43.52% 17.68b Prefetch Data: 15.89% 6.46b Demand Metadata: 40.24% 16.35b Prefetch Metadata: 0.35% 142.13m Page: 3 ------------------------------------------------------------------------ Page: 4 ------------------------------------------------------------------------ DMU Prefetch Efficiency: 220.59b Hit Ratio: 2.28% 5.03b Miss Ratio: 97.72% 215.57b Page: 5 ------------------------------------------------------------------------ Page: 6 ------------------------------------------------------------------------ ZFS Tunable (sysctl): kern.maxusers 16715 vm.kmem_size 267912790016 vm.kmem_size_scale 1 vm.kmem_size_min 0 vm.kmem_size_max 1319413950874 vfs.zfs.vol.immediate_write_sz 32768 vfs.zfs.vol.unmap_sync_enabled 0 vfs.zfs.vol.unmap_enabled 1 vfs.zfs.vol.recursive 0 vfs.zfs.vol.mode 2 vfs.zfs.sync_pass_rewrite 2 vfs.zfs.sync_pass_dont_compress 5 vfs.zfs.sync_pass_deferred_free 2 vfs.zfs.zio.dva_throttle_enabled 1 vfs.zfs.zio.exclude_metadata 0 vfs.zfs.zio.use_uma 1 vfs.zfs.zil_slog_bulk 786432 vfs.zfs.cache_flush_disable 0 vfs.zfs.zil_replay_disable 0 vfs.zfs.version.zpl 5 vfs.zfs.version.spa 5000 vfs.zfs.version.acl 1 vfs.zfs.version.ioctl 7 vfs.zfs.debug 0 vfs.zfs.super_owner 0 vfs.zfs.immediate_write_sz 32768 vfs.zfs.standard_sm_blksz 131072 vfs.zfs.dtl_sm_blksz 4096 vfs.zfs.min_auto_ashift 12 vfs.zfs.max_auto_ashift 13 vfs.zfs.vdev.queue_depth_pct 1000 vfs.zfs.vdev.write_gap_limit 4096 vfs.zfs.vdev.read_gap_limit 32768 vfs.zfs.vdev.aggregation_limit_non_rotating131072 vfs.zfs.vdev.aggregation_limit 1048576 vfs.zfs.vdev.trim_max_active 64 vfs.zfs.vdev.trim_min_active 1 vfs.zfs.vdev.scrub_max_active 2 vfs.zfs.vdev.scrub_min_active 1 vfs.zfs.vdev.async_write_max_active 10 vfs.zfs.vdev.async_write_min_active 1 vfs.zfs.vdev.async_read_max_active 3 vfs.zfs.vdev.async_read_min_active 1 vfs.zfs.vdev.sync_write_max_active 10 vfs.zfs.vdev.sync_write_min_active 10 vfs.zfs.vdev.sync_read_max_active 10 vfs.zfs.vdev.sync_read_min_active 10 vfs.zfs.vdev.max_active 1000 vfs.zfs.vdev.async_write_active_max_dirty_percent60 vfs.zfs.vdev.async_write_active_min_dirty_percent30 vfs.zfs.vdev.mirror.non_rotating_seek_inc1 vfs.zfs.vdev.mirror.non_rotating_inc 0 vfs.zfs.vdev.mirror.rotating_seek_offset1048576 vfs.zfs.vdev.mirror.rotating_seek_inc 5 vfs.zfs.vdev.mirror.rotating_inc 0 vfs.zfs.vdev.trim_on_init 1 vfs.zfs.vdev.bio_delete_disable 0 vfs.zfs.vdev.bio_flush_disable 0 vfs.zfs.vdev.cache.bshift 16 vfs.zfs.vdev.cache.size 0 vfs.zfs.vdev.cache.max 16384 vfs.zfs.vdev.default_ms_shift 29 vfs.zfs.vdev.min_ms_count 16 vfs.zfs.vdev.max_ms_count 200 vfs.zfs.vdev.trim_max_pending 10000 vfs.zfs.txg.timeout 5 vfs.zfs.trim.enabled 1 vfs.zfs.trim.max_interval 1 vfs.zfs.trim.timeout 30 vfs.zfs.trim.txg_delay 32 vfs.zfs.spa_min_slop 134217728 vfs.zfs.spa_slop_shift 5 vfs.zfs.spa_asize_inflation 24 vfs.zfs.deadman_enabled 1 vfs.zfs.deadman_checktime_ms 5000 vfs.zfs.deadman_synctime_ms 1000000 vfs.zfs.debug_flags 0 vfs.zfs.debugflags 0 vfs.zfs.recover 0 vfs.zfs.spa_load_verify_data 1 vfs.zfs.spa_load_verify_metadata 1 vfs.zfs.spa_load_verify_maxinflight 10000 vfs.zfs.max_missing_tvds_scan 0 vfs.zfs.max_missing_tvds_cachefile 2 vfs.zfs.max_missing_tvds 0 vfs.zfs.spa_load_print_vdev_tree 0 vfs.zfs.ccw_retry_interval 300 vfs.zfs.check_hostid 1 vfs.zfs.mg_fragmentation_threshold 85 vfs.zfs.mg_noalloc_threshold 0 vfs.zfs.condense_pct 200 vfs.zfs.metaslab_sm_blksz 4096 vfs.zfs.metaslab.bias_enabled 1 vfs.zfs.metaslab.lba_weighting_enabled 1 vfs.zfs.metaslab.fragmentation_factor_enabled1 vfs.zfs.metaslab.preload_enabled 1 vfs.zfs.metaslab.preload_limit 3 vfs.zfs.metaslab.unload_delay 8 vfs.zfs.metaslab.load_pct 50 vfs.zfs.metaslab.min_alloc_size 33554432 vfs.zfs.metaslab.df_free_pct 4 vfs.zfs.metaslab.df_alloc_threshold 131072 vfs.zfs.metaslab.debug_unload 0 vfs.zfs.metaslab.debug_load 0 vfs.zfs.metaslab.fragmentation_threshold70 vfs.zfs.metaslab.force_ganging 16777217 vfs.zfs.free_bpobj_enabled 1 vfs.zfs.free_max_blocks 18446744073709551615 vfs.zfs.zfs_scan_checkpoint_interval 7200 vfs.zfs.zfs_scan_legacy 0 vfs.zfs.no_scrub_prefetch 0 vfs.zfs.no_scrub_io 0 vfs.zfs.resilver_min_time_ms 3000 vfs.zfs.free_min_time_ms 1000 vfs.zfs.scan_min_time_ms 1000 vfs.zfs.scan_idle 50 vfs.zfs.scrub_delay 4 vfs.zfs.resilver_delay 2 vfs.zfs.top_maxinflight 32 vfs.zfs.delay_scale 500000 vfs.zfs.delay_min_dirty_percent 60 vfs.zfs.dirty_data_sync 67108864 vfs.zfs.dirty_data_max_percent 10 vfs.zfs.dirty_data_max_max 4294967296 vfs.zfs.dirty_data_max 4294967296 vfs.zfs.max_recordsize 1048576 vfs.zfs.default_ibs 15 vfs.zfs.default_bs 9 vfs.zfs.zfetch.array_rd_sz 1048576 vfs.zfs.zfetch.max_idistance 67108864 vfs.zfs.zfetch.max_distance 8388608 vfs.zfs.zfetch.min_sec_reap 2 vfs.zfs.zfetch.max_streams 8 vfs.zfs.prefetch_disable 0 vfs.zfs.send_holes_without_birth_time 1 vfs.zfs.mdcomp_disable 0 vfs.zfs.per_txg_dirty_frees_percent 30 vfs.zfs.nopwrite_enabled 1 vfs.zfs.dedup.prefetch 1 vfs.zfs.dbuf_cache_lowater_pct 10 vfs.zfs.dbuf_cache_hiwater_pct 10 vfs.zfs.dbuf_cache_shift 5 vfs.zfs.dbuf_cache_max_bytes 8338720256 vfs.zfs.arc_min_prescient_prefetch_ms 6 vfs.zfs.arc_min_prefetch_ms 1 vfs.zfs.l2c_only_size 0 vfs.zfs.mfu_ghost_data_esize 7915449344 vfs.zfs.mfu_ghost_metadata_esize 148436202496 vfs.zfs.mfu_ghost_size 156351651840 vfs.zfs.mfu_data_esize 29638873088 vfs.zfs.mfu_metadata_esize 1056493056 vfs.zfs.mfu_size 36613960192 vfs.zfs.mru_ghost_data_esize 5438178816 vfs.zfs.mru_ghost_metadata_esize 28938361856 vfs.zfs.mru_ghost_size 34376540672 vfs.zfs.mru_data_esize 131708334592 vfs.zfs.mru_metadata_esize 461664768 vfs.zfs.mru_size 144175309824 vfs.zfs.anon_data_esize 0 vfs.zfs.anon_metadata_esize 0 vfs.zfs.anon_size 95007232 vfs.zfs.l2arc_norw 1 vfs.zfs.l2arc_feed_again 1 vfs.zfs.l2arc_noprefetch 1 vfs.zfs.l2arc_feed_min_ms 200 vfs.zfs.l2arc_feed_secs 1 vfs.zfs.l2arc_headroom 2 vfs.zfs.l2arc_write_boost 8388608 vfs.zfs.l2arc_write_max 8388608 vfs.zfs.arc_meta_limit 66709762048 vfs.zfs.arc_free_target 1393393 vfs.zfs.arc_kmem_cache_reap_retry_ms 1000 vfs.zfs.compressed_arc_enabled 1 vfs.zfs.arc_grow_retry 60 vfs.zfs.arc_shrink_shift 7 vfs.zfs.arc_average_blocksize 8192 vfs.zfs.arc_no_grow_shift 5 vfs.zfs.arc_min 33354881024 vfs.zfs.arc_max 266839048192 vfs.zfs.abd_chunk_size 4096 Page: 7 ------------------------------------------------------------------------