Update OpenZFS module parameters (#76)
- Renamed the page to "Module Parameter" since it now applies equally to Linux and FreeBSD. - Updated spl_kmem_cache_expire, spl_kmem_cache_obj_per_slab_min, spl_kmem_cache_kmem_limit to note the last version they were included in. - Added new l2arc_mfuonly, l2arc_rebuild_blocks_min_l2size, l2arc_rebuild_enabled, and l2arc_trim_ahead options which were added in OpenZFS 2.0 for the persistent L2ARC feature. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Brian Behlendorf
@@ -1,5 +1,5 @@
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ZFS on Linux Module Parameters
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Module Parameters
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==============================
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=================
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Most of the ZFS kernel module parameters are accessible in the SysFS
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Most of the ZFS kernel module parameters are accessible in the SysFS
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``/sys/module/zfs/parameters`` directory. Current value can be observed
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``/sys/module/zfs/parameters`` directory. Current value can be observed
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@@ -140,9 +140,13 @@ ARC
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- `l2arc_headroom <#l2arc-headroom>`__
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- `l2arc_headroom <#l2arc-headroom>`__
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- `l2arc_headroom_boost <#l2arc-headroom-boost>`__
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- `l2arc_headroom_boost <#l2arc-headroom-boost>`__
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- `l2arc_meta_percent <#l2arc-meta-percent>`__
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- `l2arc_meta_percent <#l2arc-meta-percent>`__
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- `l2arc_mfuonly <#l2arc-mfuonly>`__
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- `l2arc_nocompress <#l2arc-nocompress>`__
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- `l2arc_nocompress <#l2arc-nocompress>`__
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- `l2arc_noprefetch <#l2arc-noprefetch>`__
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- `l2arc_noprefetch <#l2arc-noprefetch>`__
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- `l2arc_norw <#l2arc-norw>`__
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- `l2arc_norw <#l2arc-norw>`__
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- `l2arc_rebuild_blocks_min_l2size <#l2arc-rebuild-blocks-min-l2size>`__
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- `l2arc_rebuild_enabled <#l2arc-rebuild-enabled>`__
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- `l2arc_trim_ahead <#l2arc-trim-ahead>`__
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- `l2arc_write_boost <#l2arc-write-boost>`__
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- `l2arc_write_boost <#l2arc-write-boost>`__
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- `l2arc_write_max <#l2arc-write-max>`__
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- `l2arc_write_max <#l2arc-write-max>`__
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- `zfs_multilist_num_sublists <#zfs-multilist-num-sublists>`__
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- `zfs_multilist_num_sublists <#zfs-multilist-num-sublists>`__
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@@ -335,9 +339,13 @@ L2ARC
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- `l2arc_headroom <#l2arc-headroom>`__
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- `l2arc_headroom <#l2arc-headroom>`__
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- `l2arc_headroom_boost <#l2arc-headroom-boost>`__
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- `l2arc_headroom_boost <#l2arc-headroom-boost>`__
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- `l2arc_meta_percent <#l2arc-meta-percent>`__
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- `l2arc_meta_percent <#l2arc-meta-percent>`__
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- `l2arc_mfuonly <#l2arc-mfuonly>`__
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- `l2arc_nocompress <#l2arc-nocompress>`__
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- `l2arc_nocompress <#l2arc-nocompress>`__
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- `l2arc_noprefetch <#l2arc-noprefetch>`__
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- `l2arc_noprefetch <#l2arc-noprefetch>`__
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- `l2arc_norw <#l2arc-norw>`__
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- `l2arc_norw <#l2arc-norw>`__
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- `l2arc_rebuild_blocks_min_l2size <#l2arc-rebuild-blocks-min-l2size>`__
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- `l2arc_rebuild_enabled <#l2arc-rebuild-enabled>`__
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- `l2arc_trim_ahead <#l2arc-trim-ahead>`__
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- `l2arc_write_boost <#l2arc-write-boost>`__
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- `l2arc_write_boost <#l2arc-write-boost>`__
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- `l2arc_write_max <#l2arc-write-max>`__
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- `l2arc_write_max <#l2arc-write-max>`__
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@@ -820,9 +828,13 @@ Index
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- `l2arc_headroom <#l2arc-headroom>`__
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- `l2arc_headroom <#l2arc-headroom>`__
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- `l2arc_headroom_boost <#l2arc-headroom-boost>`__
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- `l2arc_headroom_boost <#l2arc-headroom-boost>`__
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- `l2arc_meta_percent <#l2arc-meta-percent>`__
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- `l2arc_meta_percent <#l2arc-meta-percent>`__
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- `l2arc_mfuonly <#l2arc-mfuonly>`__
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- `l2arc_nocompress <#l2arc-nocompress>`__
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- `l2arc_nocompress <#l2arc-nocompress>`__
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- `l2arc_noprefetch <#l2arc-noprefetch>`__
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- `l2arc_noprefetch <#l2arc-noprefetch>`__
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- `l2arc_norw <#l2arc-norw>`__
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- `l2arc_norw <#l2arc-norw>`__
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- `l2arc_rebuild_blocks_min_l2size <#l2arc-rebuild-blocks-min-l2size>`__
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- `l2arc_rebuild_enabled <#l2arc-rebuild-enabled>`__
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- `l2arc_trim_ahead <#l2arc-trim-ahead>`__
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- `l2arc_write_boost <#l2arc-write-boost>`__
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- `l2arc_write_boost <#l2arc-write-boost>`__
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- `l2arc_write_max <#l2arc-write-max>`__
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- `l2arc_write_max <#l2arc-write-max>`__
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- `zfs_lua_max_instrlimit <#zfs-lua-max-instrlimit>`__
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- `zfs_lua_max_instrlimit <#zfs-lua-max-instrlimit>`__
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@@ -1239,6 +1251,34 @@ This parameter limits L2ARC writes and rebuild to achieve it.
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| Versions Affected | v2.0 and later |
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| Versions Affected | v2.0 and later |
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+-------------------+-------------------------------------------------+
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+-------------------+-------------------------------------------------+
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l2arc_mfuonly
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~~~~~~~~~~~~~
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Controls whether only MFU metadata and data are cached from ARC into L2ARC.
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This may be desirable to avoid wasting space on L2ARC when reading/writing
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large amounts of data that are not expected to be accessed more than once.
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By default both MRU and MFU data and metadata are cached in the L2ARC.
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+-------------------+-------------------------------------------------+
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| l2arc_mfuonly | Notes |
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+===================+=================================================+
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| Tags | `ARC <#arc>`__, `L2ARC <#l2arc>`__ |
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+-------------------+-------------------------------------------------+
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| When to change | When accessing a large amount of data only |
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| | once. |
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+-------------------+-------------------------------------------------+
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| Data Type | boolean |
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+-------------------+-------------------------------------------------+
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| Range | 0=store MRU and MFU blocks in cache device, |
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| | 1=store MFU blocks in cache device |
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+-------------------+-------------------------------------------------+
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| Default | 0 |
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+-------------------+-------------------------------------------------+
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| Change | Dynamic |
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+-------------------+-------------------------------------------------+
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| Versions Affected | v2.0 and later |
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+-------------------+-------------------------------------------------+
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l2arc_noprefetch
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l2arc_noprefetch
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~~~~~~~~~~~~~~~~
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~~~~~~~~~~~~~~~~
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@@ -1297,6 +1337,95 @@ Disables writing to cache devices while they are being read.
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| Versions Affected | all |
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| Versions Affected | all |
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+-------------------+-------------------------------------------------+
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+-------------------+-------------------------------------------------+
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l2arc_rebuild_blocks_min_l2size
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The minimum required size (in bytes) of an L2ARC device in order to
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write log blocks in it. The log blocks are used upon importing the pool
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to rebuild the persistent L2ARC. For L2ARC devices less than 1GB the
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overhead involved offsets most of benefit so log blocks are not written
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for cache devices smaller than this.
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+---------------------------------+-----------------------------------+
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| l2arc_rebuild_blocks_min_l2size | Notes |
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+=================================+===================================+
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| Tags | `ARC <#arc>`__, |
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| | `L2ARC <#l2arc>`__ |
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+---------------------------------+-----------------------------------+
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| When to change | The cache device is small and |
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| | the pool is frequently imported. |
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+---------------------------------+-----------------------------------+
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| Data Type | bytes |
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+---------------------------------+-----------------------------------+
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| Range | 0 to UINT64_MAX |
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+---------------------------------+-----------------------------------+
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| Default | 1,073,741,824 |
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+---------------------------------+-----------------------------------+
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| Change | Dynamic |
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+---------------------------------+-----------------------------------+
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| Versions Affected | v2.0 and later |
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+---------------------------------+-----------------------------------+
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l2arc_rebuild_enabled
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~~~~~~~~~~~~~~~~~~~~~
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Rebuild the persistent L2ARC when importing a pool.
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+-----------------------+---------------------------------------------+
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| l2arc_rebuild_enabled | Notes |
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+=======================+=============================================+
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| Tags | `ARC <#arc>`__, `L2ARC <#l2arc>`__ |
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+-----------------------+---------------------------------------------+
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| When to change | If there are problems importing a pool or |
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| | attaching an L2ARC device. |
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+-----------------------+---------------------------------------------+
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| Data Type | boolean |
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+-----------------------+---------------------------------------------+
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| Range | 0=disable persistent L2ARC rebuild, |
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| | 1=enable persistent L2ARC rebuild |
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+-----------------------+---------------------------------------------+
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| Default | 1 |
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+-----------------------+---------------------------------------------+
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| Change | Dynamic |
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+-----------------------+---------------------------------------------+
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| Versions Affected | v2.0 and later |
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+-----------------------+---------------------------------------------+
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l2arc_trim_ahead
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~~~~~~~~~~~~~~~~
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Once the cache device has been filled TRIM ahead of the current write size
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``l2arc_write_max`` on L2ARC devices by this percentage. This can speed
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up future writes depending on the performance characteristics of the
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cache device.
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When set to 100% TRIM twice the space required to accommodate upcoming
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writes. A minimum of 64MB will be trimmed. If set it enables TRIM of
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the whole L2ARC device when it is added to a pool. By default, this
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option is disabled since it can put significant stress on the underlying
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storage devices.
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+-------------------+-------------------------------------------------+
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| l2arc_trim_ahead | Notes |
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+===================+=================================================+
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| Tags | `ARC <#arc>`__, `L2ARC <#l2arc>`__ |
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+-------------------+-------------------------------------------------+
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| When to change | Consider setting for cache devices which |
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| | effeciently handle TRIM commands. |
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+-------------------+-------------------------------------------------+
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| Data Type | ulong |
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+-------------------+-------------------------------------------------+
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| Units | percent of l2arc_write_max |
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+-------------------+-------------------------------------------------+
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| Range | 0 to 100 |
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+-------------------+-------------------------------------------------+
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| Default | 0 |
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+-------------------+-------------------------------------------------+
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| Change | Dynamic |
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+-------------------+-------------------------------------------------+
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| Versions Affected | v2.0 and later |
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+-------------------+-------------------------------------------------+
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l2arc_write_boost
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l2arc_write_boost
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~~~~~~~~~~~~~~~~~
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~~~~~~~~~~~~~~~~~
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@@ -8925,7 +9054,7 @@ Data Type bitmask
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Range 0x01 - Aging (illumos), 0x02 - Low memory (Linux)
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Range 0x01 - Aging (illumos), 0x02 - Low memory (Linux)
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Default 0x02
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Default 0x02
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Change Dynamic
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Change Dynamic
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Versions Affected v0.6.1
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Versions Affected v0.6.1 to v0.8.x
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===================== =================================================
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===================== =================================================
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spl_kmem_cache_kmem_limit
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spl_kmem_cache_kmem_limit
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@@ -8966,7 +9095,7 @@ Units pages
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Range TBD
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Range TBD
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Default PAGE_SIZE / 4
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Default PAGE_SIZE / 4
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Change Dynamic
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Change Dynamic
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Versions Affected v0.7.0
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Versions Affected v0.7.0 to v0.8.x
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========================= ====================
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========================= ====================
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spl_kmem_cache_max_size
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spl_kmem_cache_max_size
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@@ -9012,7 +9141,7 @@ Units kmem cache objects
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Range TBD
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Range TBD
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Default 8
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Default 8
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Change Dynamic
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Change Dynamic
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Versions Affected v0.7.0
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Versions Affected v0.7.0 to v0.8.x
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=========================== ====================
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=========================== ====================
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spl_kmem_cache_obj_per_slab_min
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spl_kmem_cache_obj_per_slab_min
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