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48 lines
2.3 KiB
Markdown
48 lines
2.3 KiB
Markdown
# Tweaking Performance
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mergerfs is at its is a proxy and therefore its theoretical max
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performance is that of the underlying devices. However, given it is a
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FUSE based filesystem working from userspace there is an increase in
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overhead relative to kernel based solutions. That said the performance
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can match the theoretical max but it depends greatly on the system's
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configuration. Especially when adding network filesystems into the mix
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there are many variables which can impact performance. Device speeds
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and latency, network speeds and latency, concurrency and parallel
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limits of the hardware, read/write sizes, etc.
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While some settings can impact performance they are all **functional**
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in nature. Meaning they change mergerfs' behavior in some way. As a
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result there is no such thing as a "performance mode".
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If you're having performance issues please look over the suggestions
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below and the [benchmarking section.](benchmarking.md)
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NOTE: Be sure to [read about these features](config/options.md) before
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changing them to understand how functionality will change.
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* test theoretical performance using `nullrw` or mounting a ram disk
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* change read or process [thread pools](config/threads.md)
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* change [func.readdir](config/func_readdir.md)
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* increase [readahead](config/readahead.md): `readahead=1024`
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* disable `security_capability` and/or `xattr`
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* increase cache timeouts [cache.attr](config/cache.md#cacheattr),
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[cache.entry](config/cache.md#cacheentry),
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[cache.negative_entry](config/cache.md#cachenegative_entry)
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* enable (or disable) page caching ([cache.files](config/cache.md#cachefiles))
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* enable `parallel-direct-writes`
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* enable [cache.writeback](config/cache.md#cachewriteback)
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* enable [cache.statfs](config/cache.md#cachestatfs)
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* enable [cache.symlinks](config/cache.md#cachesymlinks)
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* enable [cache.readdir](config/cache.md#cachereaddir)
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* disable `posix_acl`
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* disable `async_read`
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* use [symlinkify](config/symlinkify.md) if your data is largely
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static and read-only
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* use [tiered cache](usage_patterns.md) devices
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* use LVM and LVM cache to place a SSD in front of your HDDs
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If you come across a setting that significantly impacts performance
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please [contact trapexit](support.md) so he may investigate further. Please test
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both against your normal setup, a singular branch, and with
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`nullrw=true`
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