.\" Copyright (c) 2013 by Turbo Fredriksson <turbo@bayour.com>. All rights reserved.
.\" Copyright (c) 2019, 2021 by Delphix. All rights reserved.
.\" Copyright (c) 2019 Datto Inc.
+.\" Copyright (c) 2023, 2024 Klara, Inc.
.\" The contents of this file are subject to the terms of the Common Development
.\" and Distribution License (the "License"). You may not use this file except
.\" in compliance with the License. You can obtain a copy of the license at
.\" own identifying information:
.\" Portions Copyright [yyyy] [name of copyright owner]
.\"
-.Dd November 9, 2022
+.Dd January 9, 2024
.Dt ZFS 4
.Os
.
.It Sy l2arc_feed_secs Ns = Ns Sy 1 Pq u64
Seconds between L2ARC writing.
.
-.It Sy l2arc_headroom Ns = Ns Sy 2 Pq u64
+.It Sy l2arc_headroom Ns = Ns Sy 8 Pq u64
How far through the ARC lists to search for L2ARC cacheable content,
expressed as a multiplier of
.Sy l2arc_write_max .
.It Sy l2arc_norw Ns = Ns Sy 0 Ns | Ns 1 Pq int
No reads during writes.
.
-.It Sy l2arc_write_boost Ns = Ns Sy 8388608 Ns B Po 8 MiB Pc Pq u64
+.It Sy l2arc_write_boost Ns = Ns Sy 33554432 Ns B Po 32 MiB Pc Pq u64
Cold L2ARC devices will have
.Sy l2arc_write_max
increased by this amount while they remain cold.
.
-.It Sy l2arc_write_max Ns = Ns Sy 8388608 Ns B Po 8 MiB Pc Pq u64
+.It Sy l2arc_write_max Ns = Ns Sy 33554432 Ns B Po 32 MiB Pc Pq u64
Max write bytes per interval.
.
.It Sy l2arc_rebuild_enabled Ns = Ns Sy 1 Ns | Ns 0 Pq int
Make some blocks above a certain size be gang blocks.
This option is used by the test suite to facilitate testing.
.
+.It Sy metaslab_force_ganging_pct Ns = Ns Sy 3 Ns % Pq uint
+For blocks that could be forced to be a gang block (due to
+.Sy metaslab_force_ganging ) ,
+force this many of them to be gang blocks.
+.
+.It Sy brt_zap_prefetch Ns = Ns Sy 1 Ns | Ns 0 Pq int
+Controls prefetching BRT records for blocks which are going to be cloned.
+.
+.It Sy brt_zap_default_bs Ns = Ns Sy 12 Po 4 KiB Pc Pq int
+Default BRT ZAP data block size as a power of 2. Note that changing this after
+creating a BRT on the pool will not affect existing BRTs, only newly created
+ones.
+.
+.It Sy brt_zap_default_ibs Ns = Ns Sy 12 Po 4 KiB Pc Pq int
+Default BRT ZAP indirect block size as a power of 2. Note that changing this
+after creating a BRT on the pool will not affect existing BRTs, only newly
+created ones.
+.
+.It Sy ddt_zap_default_bs Ns = Ns Sy 15 Po 32 KiB Pc Pq int
+Default DDT ZAP data block size as a power of 2. Note that changing this after
+creating a DDT on the pool will not affect existing DDTs, only newly created
+ones.
+.
+.It Sy ddt_zap_default_ibs Ns = Ns Sy 15 Po 32 KiB Pc Pq int
+Default DDT ZAP indirect block size as a power of 2. Note that changing this
+after creating a DDT on the pool will not affect existing DDTs, only newly
+created ones.
+.
+.It Sy zfs_default_bs Ns = Ns Sy 9 Po 512 B Pc Pq int
+Default dnode block size as a power of 2.
+.
+.It Sy zfs_default_ibs Ns = Ns Sy 17 Po 128 KiB Pc Pq int
+Default dnode indirect block size as a power of 2.
+.
.It Sy zfs_history_output_max Ns = Ns Sy 1048576 Ns B Po 1 MiB Pc Pq u64
When attempting to log an output nvlist of an ioctl in the on-disk history,
the output will not be stored if it is larger than this size (in bytes).
When a vdev is added, target this number of metaslabs per top-level vdev.
.
.It Sy zfs_vdev_default_ms_shift Ns = Ns Sy 29 Po 512 MiB Pc Pq uint
-Default limit for metaslab size.
+Default lower limit for metaslab size.
+.
+.It Sy zfs_vdev_max_ms_shift Ns = Ns Sy 34 Po 16 GiB Pc Pq uint
+Default upper limit for metaslab size.
.
.It Sy zfs_vdev_max_auto_ashift Ns = Ns Sy 14 Pq uint
-Maximum ashift used when optimizing for logical \[->] physical sector size on new
+Maximum ashift used when optimizing for logical \[->] physical sector size on
+new
top-level vdevs.
May be increased up to
.Sy ASHIFT_MAX Po 16 Pc ,
.It Sy metaslab_preload_enabled Ns = Ns Sy 1 Ns | Ns 0 Pq int
Enable metaslab group preloading.
.
+.It Sy metaslab_preload_limit Ns = Ns Sy 10 Pq uint
+Maximum number of metaslabs per group to preload
+.
+.It Sy metaslab_preload_pct Ns = Ns Sy 50 Pq uint
+Percentage of CPUs to run a metaslab preload taskq
+.
.It Sy metaslab_lba_weighting_enabled Ns = Ns Sy 1 Ns | Ns 0 Pq int
Give more weight to metaslabs with lower LBAs,
assuming they have greater bandwidth,
TXGs must pass before unloading will occur.
.
.It Sy reference_history Ns = Ns Sy 3 Pq uint
-Maximum reference holders being tracked when reference_tracking_enable is active.
+Maximum reference holders being tracked when reference_tracking_enable is
+active.
+.It Sy raidz_expand_max_copy_bytes Ns = Ns Sy 160MB Pq ulong
+Max amount of memory to use for RAID-Z expansion I/O.
+This limits how much I/O can be outstanding at once.
+.
+.It Sy raidz_expand_max_reflow_bytes Ns = Ns Sy 0 Pq ulong
+For testing, pause RAID-Z expansion when reflow amount reaches this value.
+.
+.It Sy raidz_io_aggregate_rows Ns = Ns Sy 4 Pq ulong
+For expanded RAID-Z, aggregate reads that have more rows than this.
+.
+.It Sy reference_history Ns = Ns Sy 3 Pq int
+Maximum reference holders being tracked when reference_tracking_enable is
+active.
.
.It Sy reference_tracking_enable Ns = Ns Sy 0 Ns | Ns 1 Pq int
Track reference holders to
particularly if they operate close to quota or capacity limits.
.
.It Sy spa_load_print_vdev_tree Ns = Ns Sy 0 Ns | Ns 1 Pq int
-Whether to print the vdev tree in the debugging message buffer during pool import.
+Whether to print the vdev tree in the debugging message buffer during pool
+import.
.
.It Sy spa_load_verify_data Ns = Ns Sy 1 Ns | Ns 0 Pq int
Whether to traverse data blocks during an "extreme rewind"
most ZPL operations (e.g. write, create) will return
.Sy ENOSPC .
.
+.It Sy spa_num_allocators Ns = Ns Sy 4 Pq int
+Determines the number of block alloctators to use per spa instance.
+Capped by the number of actual CPUs in the system.
+.Pp
+Note that setting this value too high could result in performance
+degredation and/or excess fragmentation.
+.
.It Sy spa_upgrade_errlog_limit Ns = Ns Sy 0 Pq uint
Limits the number of on-disk error log entries that will be converted to the
new format when enabling the
However, this is limited by
.Sy dmu_prefetch_max .
.
-.It Sy zfetch_array_rd_sz Ns = Ns Sy 1048576 Ns B Po 1 MiB Pc Pq u64
-If prefetching is enabled, disable prefetching for reads larger than this size.
+.It Sy zap_micro_max_size Ns = Ns Sy 131072 Ns B Po 128 KiB Pc Pq int
+Maximum micro ZAP size.
+A micro ZAP is upgraded to a fat ZAP, once it grows beyond the specified size.
.
.It Sy zfetch_min_distance Ns = Ns Sy 4194304 Ns B Po 4 MiB Pc Pq uint
Min bytes to prefetch per stream.
which indicates that a percent which is based on
.Sy zfs_arc_dnode_limit_percent
of the ARC meta buffers that may be used for dnodes.
-.Pp
-Also see
-.Sy zfs_arc_meta_prune
-which serves a similar purpose but is used
-when the amount of metadata in the ARC exceeds
-.Sy zfs_arc_meta_limit
-rather than in response to overall demand for non-metadata.
-.
.It Sy zfs_arc_dnode_limit_percent Ns = Ns Sy 10 Ns % Pq u64
Percentage that can be consumed by dnodes of ARC meta buffers.
.Pp
If
.Sy 0 ,
then the max size of ARC is determined by the amount of system memory installed.
-Under Linux, half of system memory will be used as the limit.
-Under
-.Fx ,
-the larger of
+The larger of
.Sy all_system_memory No \- Sy 1 GiB
and
.Sy 5/8 No \(mu Sy all_system_memory
while running, and reducing it below the current ARC size will not cause
the ARC to shrink without memory pressure to induce shrinking.
.
-.It Sy zfs_arc_meta_adjust_restarts Ns = Ns Sy 4096 Pq uint
-The number of restart passes to make while scanning the ARC attempting
-the free buffers in order to stay below the
-.Sy fs_arc_meta_limit .
-This value should not need to be tuned but is available to facilitate
-performance analysis.
-.
-.It Sy zfs_arc_meta_limit Ns = Ns Sy 0 Ns B Pq u64
-The maximum allowed size in bytes that metadata buffers are allowed to
-consume in the ARC.
-When this limit is reached, metadata buffers will be reclaimed,
-even if the overall
-.Sy arc_c_max
-has not been reached.
-It defaults to
-.Sy 0 ,
-which indicates that a percentage based on
-.Sy zfs_arc_meta_limit_percent
-of the ARC may be used for metadata.
-.Pp
-This value my be changed dynamically, except that must be set to an explicit value
-.Pq cannot be set back to Sy 0 .
-.
-.It Sy zfs_arc_meta_limit_percent Ns = Ns Sy 75 Ns % Pq u64
-Percentage of ARC buffers that can be used for metadata.
-.Pp
-See also
-.Sy zfs_arc_meta_limit ,
-which serves a similar purpose but has a higher priority if nonzero.
-.
-.It Sy zfs_arc_meta_min Ns = Ns Sy 0 Ns B Pq u64
-The minimum allowed size in bytes that metadata buffers may consume in
-the ARC.
-.
-.It Sy zfs_arc_meta_prune Ns = Ns Sy 10000 Pq int
-The number of dentries and inodes to be scanned looking for entries
-which can be dropped.
-This may be required when the ARC reaches the
-.Sy zfs_arc_meta_limit
-because dentries and inodes can pin buffers in the ARC.
-Increasing this value will cause to dentry and inode caches
-to be pruned more aggressively.
-Setting this value to
-.Sy 0
-will disable pruning the inode and dentry caches.
-.
-.It Sy zfs_arc_meta_strategy Ns = Ns Sy 1 Ns | Ns 0 Pq uint
-Define the strategy for ARC metadata buffer eviction (meta reclaim strategy):
-.Bl -tag -compact -offset 4n -width "0 (META_ONLY)"
-.It Sy 0 Pq META_ONLY
-evict only the ARC metadata buffers
-.It Sy 1 Pq BALANCED
-additional data buffers may be evicted if required
-to evict the required number of metadata buffers.
-.El
+.It Sy zfs_arc_meta_balance Ns = Ns Sy 500 Pq uint
+Balance between metadata and data on ghost hits.
+Values above 100 increase metadata caching by proportionally reducing effect
+of ghost data hits on target data/metadata rate.
.
.It Sy zfs_arc_min Ns = Ns Sy 0 Ns B Pq u64
Min size of ARC in bytes.
of the target size, and block allocations by
.Em 0.6% .
.
-.It Sy zfs_arc_p_min_shift Ns = Ns Sy 0 Pq uint
-If nonzero, this will update
-.Sy arc_p_min_shift Pq default Sy 4
-with the new value.
-.Sy arc_p_min_shift No is used as a shift of Sy arc_c
-when calculating the minumum
-.Sy arc_p No size.
-.
-.It Sy zfs_arc_p_dampener_disable Ns = Ns Sy 1 Ns | Ns 0 Pq int
-Disable
-.Sy arc_p
-adapt dampener, which reduces the maximum single adjustment to
-.Sy arc_p .
-.
.It Sy zfs_arc_shrink_shift Ns = Ns Sy 0 Pq uint
If nonzero, this will update
.Sy arc_shrink_shift Pq default Sy 7
(currently 10 checksums over 10 seconds)
or else the daemon may not trigger any action.
.
-.It Sy zfs_commit_timeout_pct Ns = Ns Sy 5 Ns % Pq uint
+.It Sy zfs_commit_timeout_pct Ns = Ns Sy 10 Ns % Pq uint
This controls the amount of time that a ZIL block (lwb) will remain "open"
when it isn't "full", and it has a thread waiting for it to be committed to
stable storage.
Intended for use with the test suite to throttle vdev removal speed.
.
.It Sy zfs_condense_indirect_obsolete_pct Ns = Ns Sy 25 Ns % Pq uint
-Minimum percent of obsolete bytes in vdev mapping required to attempt to condense
+Minimum percent of obsolete bytes in vdev mapping required to attempt to
+condense
.Pq see Sy zfs_condense_indirect_vdevs_enable .
Intended for use with the test suite
to facilitate triggering condensing as needed.
bytes of memory and if the obsolete space map object uses more than
.Sy zfs_condense_max_obsolete_bytes
bytes on-disk.
-The condensing process is an attempt to save memory by removing obsolete mappings.
+The condensing process is an attempt to save memory by removing obsolete
+mappings.
.
.It Sy zfs_condense_max_obsolete_bytes Ns = Ns Sy 1073741824 Ns B Po 1 GiB Pc Pq u64
Only attempt to condense indirect vdev mappings if the on-disk size
same object.
.
.It Sy zfs_slow_io_events_per_second Ns = Ns Sy 20 Ns /s Pq int
-Rate limit delay and deadman zevents (which report slow I/O operations) to this many per
+Rate limit delay and deadman zevents (which report slow I/O operations) to this
+many per
second.
.
.It Sy zfs_unflushed_max_mem_amt Ns = Ns Sy 1073741824 Ns B Po 1 GiB Pc Pq u64
will be deleted asynchronously, while smaller files are deleted synchronously.
Decreasing this value will reduce the time spent in an
.Xr unlink 2
-system call, at the expense of a longer delay before the freed space is available.
+system call, at the expense of a longer delay before the freed space is
+available.
This only applies on Linux.
.
.It Sy zfs_dirty_data_max Ns = Pq int
.No See Sx ZFS TRANSACTION DELAY .
.Pp
Defaults to
-.Sy physical_ram/4 ,
+.Sy min(physical_ram/4, 4GiB) ,
+or
+.Sy min(physical_ram/4, 1GiB)
+for 32-bit systems.
.
.It Sy zfs_dirty_data_max_max_percent Ns = Ns Sy 25 Ns % Pq uint
Maximum allowable value of
cleared out after transaction group sync.
Because of some overhead, it should be set at least 2 times the size of
.Sy zfs_dirty_data_max
-.No to prevent harming normal write throughput.
+.No to prevent harming normal write throughput .
It also should be smaller than the size of the slog device if slog is present.
.Pp
Defaults to
results in vector instructions
from the respective CPU instruction set being used.
.
+.It Sy zfs_bclone_enabled Ns = Ns Sy 1 Ns | Ns 0 Pq int
+Enable the experimental block cloning feature.
+If this setting is 0, then even if feature@block_cloning is enabled,
+attempts to clone blocks will act as though the feature is disabled.
+.
+.It Sy zfs_bclone_wait_dirty Ns = Ns Sy 0 Ns | Ns 1 Pq int
+When set to 1 the FICLONE and FICLONERANGE ioctls wait for dirty data to be
+written to disk.
+This allows the clone operation to reliably succeed when a file is
+modified and then immediately cloned.
+For small files this may be slower than making a copy of the file.
+Therefore, this setting defaults to 0 which causes a clone operation to
+immediately fail when encountering a dirty block.
+.
.It Sy zfs_blake3_impl Ns = Ns Sy fastest Pq string
Select a BLAKE3 implementation.
.Pp
interpolated.
.No See Sx ZFS I/O SCHEDULER .
.
-.It Sy zfs_vdev_async_write_max_active Ns = Ns Sy 30 Pq uint
+.It Sy zfs_vdev_async_write_max_active Ns = Ns Sy 10 Pq uint
Maximum asynchronous write I/O operations active to each device.
.No See Sx ZFS I/O SCHEDULER .
.
Also see
.Sy zio_dva_throttle_enabled .
.
+.It Sy zfs_vdev_def_queue_depth Ns = Ns Sy 32 Pq uint
+Default queue depth for each vdev IO allocator.
+Higher values allow for better coalescing of sequential writes before sending
+them to the disk, but can increase transaction commit times.
+.
.It Sy zfs_vdev_failfast_mask Ns = Ns Sy 1 Pq uint
Defines if the driver should retire on a given error type.
The following options may be bitwise-ored together:
4 Driver No driver retries on driver errors.
.TE
.
+.It Sy zfs_vdev_disk_max_segs Ns = Ns Sy 0 Pq uint
+Maximum number of segments to add to a BIO (min 4).
+If this is higher than the maximum allowed by the device queue or the kernel
+itself, it will be clamped.
+Setting it to zero will cause the kernel's ideal size to be used.
+This parameter only applies on Linux.
+.
.It Sy zfs_expire_snapshot Ns = Ns Sy 300 Ns s Pq int
Time before expiring
.Pa .zfs/snapshot .
* 2 ZFS_DEBUG_DBUF_VERIFY Enable extra dbuf verifications.
* 4 ZFS_DEBUG_DNODE_VERIFY Enable extra dnode verifications.
8 ZFS_DEBUG_SNAPNAMES Enable snapshot name verification.
- 16 ZFS_DEBUG_MODIFY Check for illegally modified ARC buffers.
+* 16 ZFS_DEBUG_MODIFY Check for illegally modified ARC buffers.
64 ZFS_DEBUG_ZIO_FREE Enable verification of block frees.
128 ZFS_DEBUG_HISTOGRAM_VERIFY Enable extra spacemap histogram verifications.
256 ZFS_DEBUG_METASLAB_VERIFY Verify space accounting on disk matches in-memory \fBrange_trees\fP.
4096 ZFS_DEBUG_LOG_SPACEMAP Verify that the log summary is consistent with the spacemap log
and enable \fBzfs_dbgmsgs\fP for metaslab loading and flushing.
.TE
-.Sy \& * No Requires debug build.
+.Sy \& * No Requires debug build .
.
.It Sy zfs_btree_verify_intensity Ns = Ns Sy 0 Pq uint
Enables btree verification.
4 Verify element order. (expensive)
* 5 Verify unused memory is poisoned. (expensive)
.TE
-.Sy \& * No Requires debug build.
+.Sy \& * No Requires debug build .
.
.It Sy zfs_free_leak_on_eio Ns = Ns Sy 0 Ns | Ns 1 Pq int
If destroy encounters an
allocations.
The default value of
.Sy 0
-disables the feature and causes all metaslab groups to be eligible for allocations.
+disables the feature and causes all metaslab groups to be eligible for
+allocations.
.Pp
This parameter allows one to deal with pools having heavily imbalanced
vdevs such as would be the case when a new vdev has been added.
into the special allocation class.
.
.It Sy zfs_multihost_history Ns = Ns Sy 0 Pq uint
-Historical statistics for this many latest multihost updates will be available in
+Historical statistics for this many latest multihost updates will be available
+in
.Pa /proc/spl/kstat/zfs/ Ns Ao Ar pool Ac Ns Pa /multihost .
.
.It Sy zfs_multihost_interval Ns = Ns Sy 1000 Ns ms Po 1 s Pc Pq u64
.It Sy zfs_per_txg_dirty_frees_percent Ns = Ns Sy 30 Ns % Pq u64
Control percentage of dirtied indirect blocks from frees allowed into one TXG.
After this threshold is crossed, additional frees will wait until the next TXG.
-.Sy 0 No disables this throttle.
+.Sy 0 No disables this throttle .
.
.It Sy zfs_prefetch_disable Ns = Ns Sy 0 Ns | Ns 1 Pq int
Disable predictive prefetch.
resilvered.
This is enabled by default and strongly recommended.
.
-.It Sy zfs_rebuild_vdev_limit Ns = Ns Sy 33554432 Ns B Po 32 MiB Pc Pq u64
+.It Sy zfs_rebuild_vdev_limit Ns = Ns Sy 67108864 Ns B Po 64 MiB Pc Pq u64
Maximum amount of I/O that can be concurrently issued for a sequential
resilver per leaf device, given in bytes.
.
Intended to be used during pool repair or recovery to
stop resilvering when the pool is next imported.
.
+.It Sy zfs_scrub_after_expand Ns = Ns Sy 1 Ns | Ns 0 Pq int
+Automatically start a pool scrub after a RAIDZ expansion completes
+in order to verify the checksums of all blocks which have been
+copied during the expansion.
+This is enabled by default and strongly recommended.
+.
.It Sy zfs_scrub_min_time_ms Ns = Ns Sy 1000 Ns ms Po 1 s Pc Pq uint
Scrubs are processed by the sync thread.
While scrubbing, it will spend at least this much time
working on a scrub between TXG flushes.
.
+.It Sy zfs_scrub_error_blocks_per_txg Ns = Ns Sy 4096 Pq uint
+Error blocks to be scrubbed in one txg.
+.
.It Sy zfs_scan_checkpoint_intval Ns = Ns Sy 7200 Ns s Po 2 hour Pc Pq uint
To preserve progress across reboots, the sequential scan algorithm periodically
needs to stop metadata scanning and issue all the verification I/O to disk.
while a lower number indicates we care more about the size of the extent without
considering the gaps within a segment.
This value is only tunable upon module insertion.
-Changing the value afterwards will have no effect on scrub or resilver performance.
+Changing the value afterwards will have no effect on scrub or resilver
+performance.
.
.It Sy zfs_scan_issue_strategy Ns = Ns Sy 0 Pq uint
Determines the order that data will be verified while scrubbing or resilvering:
to coalesce and increase the segment size.
.It Sy 0
.No Use strategy Sy 1 No during normal verification
-.No and strategy Sy 2 No while taking a checkpoint.
+.No and strategy Sy 2 No while taking a checkpoint .
.El
.
.It Sy zfs_scan_legacy Ns = Ns Sy 0 Ns | Ns 1 Pq int
The fraction of the hard limit used to determined the soft limit for I/O sorting
by the sequential scan algorithm.
When we cross this limit from below no action is taken.
-When we cross this limit from above it is because we are issuing verification I/O.
+When we cross this limit from above it is because we are issuing verification
+I/O.
In this case (unless the metadata scan is done) we stop issuing verification I/O
and start scanning metadata again until we get to the hard limit.
.
+.It Sy zfs_scan_report_txgs Ns = Ns Sy 0 Ns | Ns 1 Pq uint
+When reporting resilver throughput and estimated completion time use the
+performance observed over roughly the last
+.Sy zfs_scan_report_txgs
+TXGs.
+When set to zero performance is calculated over the time between checkpoints.
+.
.It Sy zfs_scan_strict_mem_lim Ns = Ns Sy 0 Ns | Ns 1 Pq int
Enforce tight memory limits on pool scans when a sequential scan is in progress.
When disabled, the memory limit may be exceeded by fast disks.
Freezes a scrub/resilver in progress without actually pausing it.
Intended for testing/debugging.
.
-.It Sy zfs_scan_vdev_limit Ns = Ns Sy 4194304 Ns B Po 4 MiB Pc Pq int
+.It Sy zfs_scan_vdev_limit Ns = Ns Sy 16777216 Ns B Po 16 MiB Pc Pq int
Maximum amount of data that can be concurrently issued at once for scrubs and
resilvers per leaf device, given in bytes.
.
.
.It Sy zfs_special_class_metadata_reserve_pct Ns = Ns Sy 25 Ns % Pq uint
Only allow small data blocks to be allocated on the special and dedup vdev
-types when the available free space percentage on these vdevs exceeds this value.
+types when the available free space percentage on these vdevs exceeds this
+value.
This ensures reserved space is available for pool metadata as the
special vdevs approach capacity.
.
The
.Em 128 KiB
allocations are especially detrimental to performance
-on highly fragmented systems, which may have very few free segments of this size,
+on highly fragmented systems, which may have very few free segments of this
+size,
and may need to load new metaslabs to satisfy these allocations.
.
.It Sy zfs_sync_pass_rewrite Ns = Ns Sy 2 Pq uint
Rewrite new block pointers starting in this pass.
.
-.It Sy zfs_sync_taskq_batch_pct Ns = Ns Sy 75 Ns % Pq int
-This controls the number of threads used by
-.Sy dp_sync_taskq .
-The default value of
-.Sy 75%
-will create a maximum of one thread per CPU.
-.
.It Sy zfs_trim_extent_bytes_max Ns = Ns Sy 134217728 Ns B Po 128 MiB Pc Pq uint
Maximum size of TRIM command.
-Larger ranges will be split into chunks no larger than this value before issuing.
+Larger ranges will be split into chunks no larger than this value before
+issuing.
.
.It Sy zfs_trim_extent_bytes_min Ns = Ns Sy 32768 Ns B Po 32 KiB Pc Pq uint
Minimum size of TRIM commands.
.
.It Sy zfs_trim_metaslab_skip Ns = Ns Sy 0 Ns | Ns 1 Pq uint
Skip uninitialized metaslabs during the TRIM process.
-This option is useful for pools constructed from large thinly-provisioned devices
+This option is useful for pools constructed from large thinly-provisioned
+devices
where TRIM operations are slow.
As a pool ages, an increasing fraction of the pool's metaslabs
will be initialized, progressively degrading the usefulness of this option.
before the recently trimmed space is available for use by the device.
.Pp
Increasing this value will allow frees to be aggregated for a longer time.
-This will result is larger TRIM operations and potentially increased memory usage.
+This will result is larger TRIM operations and potentially increased memory
+usage.
Decreasing this value will have the opposite effect.
The default of
.Sy 32
.Pa /proc/spl/kstat/zfs/ Ns Ao Ar pool Ac Ns Pa /TXGs .
.
.It Sy zfs_txg_timeout Ns = Ns Sy 5 Ns s Pq uint
-Flush dirty data to disk at least every this many seconds (maximum TXG duration).
-.
-.It Sy zfs_vdev_aggregate_trim Ns = Ns Sy 0 Ns | Ns 1 Pq uint
-Allow TRIM I/O operations to be aggregated.
-This is normally not helpful because the extents to be trimmed
-will have been already been aggregated by the metaslab.
-This option is provided for debugging and performance analysis.
+Flush dirty data to disk at least every this many seconds (maximum TXG
+duration).
.
.It Sy zfs_vdev_aggregation_limit Ns = Ns Sy 1048576 Ns B Po 1 MiB Pc Pq uint
Max vdev I/O aggregation size.
.It Sy zfs_vdev_aggregation_limit_non_rotating Ns = Ns Sy 131072 Ns B Po 128 KiB Pc Pq uint
Max vdev I/O aggregation size for non-rotating media.
.
-.It Sy zfs_vdev_cache_bshift Ns = Ns Sy 16 Po 64 KiB Pc Pq uint
-Shift size to inflate reads to.
-.
-.It Sy zfs_vdev_cache_max Ns = Ns Sy 16384 Ns B Po 16 KiB Pc Pq uint
-Inflate reads smaller than this value to meet the
-.Sy zfs_vdev_cache_bshift
-size
-.Pq default Sy 64 KiB .
-.
-.It Sy zfs_vdev_cache_size Ns = Ns Sy 0 Pq uint
-Total size of the per-disk cache in bytes.
-.Pp
-Currently this feature is disabled, as it has been found to not be helpful
-for performance and in some cases harmful.
-.
.It Sy zfs_vdev_mirror_rotating_inc Ns = Ns Sy 0 Pq int
A number by which the balancing algorithm increments the load calculation for
the purpose of selecting the least busy mirror member when an I/O operation
.
.It Sy zfs_vdev_mirror_non_rotating_seek_inc Ns = Ns Sy 1 Pq int
A number by which the balancing algorithm increments the load calculation for
-the purpose of selecting the least busy mirror member when an I/O operation lacks
+the purpose of selecting the least busy mirror member when an I/O operation
+lacks
locality as defined by the
.Sy zfs_vdev_mirror_rotating_seek_offset .
Operations within this that are not immediately following the previous operation
.Pq typically to Sy 36 KiB
can improve performance.
.
+.It Sy zil_maxcopied Ns = Ns Sy 7680 Ns B Po 7.5 KiB Pc Pq uint
+This sets the maximum number of write bytes logged via WR_COPIED.
+It tunes a tradeoff between additional memory copy and possibly worse log
+space efficiency vs additional range lock/unlock.
+.
.It Sy zil_nocacheflush Ns = Ns Sy 0 Ns | Ns 1 Pq int
Disable the cache flush commands that are normally sent to disk by
the ZIL after an LWB write has completed.
Disable intent logging replay.
Can be disabled for recovery from corrupted ZIL.
.
-.It Sy zil_slog_bulk Ns = Ns Sy 786432 Ns B Po 768 KiB Pc Pq u64
+.It Sy zil_slog_bulk Ns = Ns Sy 67108864 Ns B Po 64 MiB Pc Pq u64
Limit SLOG write size per commit executed with synchronous priority.
Any writes above that will be executed with lower (asynchronous) priority
to limit potential SLOG device abuse by single active ZIL writer.
However, if there are fewer than
.Sy zfs_embedded_slog_min_ms
metaslabs in the vdev, this functionality is disabled.
-This ensures that we don't set aside an unreasonable amount of space for the ZIL.
+This ensures that we don't set aside an unreasonable amount of space for the
+ZIL.
.
.It Sy zstd_earlyabort_pass Ns = Ns Sy 1 Pq uint
Whether heuristic for detection of incompressible data with zstd levels >= 3
.Sy 0 ,
generate a system-dependent value close to 6 threads per taskq.
.
+.It Sy zio_taskq_wr_iss_ncpus Ns = Ns Sy 0 Pq uint
+Determines the number of CPUs to run write issue taskqs.
+.Pp
+When 0 (the default), the value to use is computed internally
+as the number of actual CPUs in the system divided by the
+.Sy spa_num_allocators
+value.
+.
+.It Sy zio_taskq_read Ns = Ns Sy fixed,1,8 null scale null Pq charp
+Set the queue and thread configuration for the IO read queues.
+This is an advanced debugging parameter.
+Don't change this unless you understand what it does.
+.
+.It Sy zio_taskq_write Ns = Ns Sy sync fixed,1,5 scale fixed,1,5 Pq charp
+Set the queue and thread configuration for the IO write queues.
+This is an advanced debugging parameter.
+Don't change this unless you understand what it does.
+.
.It Sy zvol_inhibit_dev Ns = Ns Sy 0 Ns | Ns 1 Pq uint
Do not create zvol device nodes.
This may slightly improve startup time on
Iteration through the I/O classes is done in the order specified above.
No further operations are issued
if the aggregate maximum number of concurrent operations has been hit,
-or if there are no operations queued for an I/O class that has not hit its maximum.
+or if there are no operations queued for an I/O class that has not hit its
+maximum.
Every time an I/O operation is queued or an operation completes,
the scheduler looks for new operations to issue.
.Pp
according to the amount of dirty data in the pool.
Since both throughput and latency typically increase with the number of
concurrent operations issued to physical devices, reducing the
-burstiness in the number of concurrent operations also stabilizes the
-response time of operations from other – and in particular synchronous – queues.
+burstiness in the number of simultaneous operations also stabilizes the
+response time of operations from other queues, in particular synchronous ones.
In broad strokes, the I/O scheduler will issue more concurrent operations
-from the async write queue as there's more dirty data in the pool.
+from the async write queue as there is more dirty data in the pool.
.
.Ss Async Writes
The number of concurrent operations issued for the async write I/O class
has failed to keep up with the incoming write rate.
The scale of the curve is defined by
.Sy zfs_delay_scale .
-Roughly speaking, this variable determines the amount of delay at the midpoint of the curve.
+Roughly speaking, this variable determines the amount of delay at the midpoint
+of the curve.
.Bd -literal
delay
10ms +-------------------------------------------------------------*+
projects / mirror_zfs.git / blobdiff