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Update mkdwarfs man page

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Marcus Holland-Moritz 2020-12-10 21:23:12 +01:00
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@ -94,9 +94,9 @@ Most other options are concerned with compression tuning:
The compression algorithm and configuration used for the metadata. The compression algorithm and configuration used for the metadata.
Takes the same arguments as `--compression` above. The metadata has been Takes the same arguments as `--compression` above. The metadata has been
optimized for very little redundancy and leaving it uncompressed, the optimized for very little redundancy and leaving it uncompressed, the
default for all levels below 8, has the benefit that it can be mapped default for all levels below 7, has the benefit that it can be mapped
to memory and used directly. This significantly improves mount time for to memory and used directly. This improves mount time for large file
large file systems compared to e.g. an lzma compressed metadata block. systems compared to e.g. an lzma compressed metadata block.
* `--recompress`: * `--recompress`:
Take an existing DwarFS filesystem and recompress it using a different Take an existing DwarFS filesystem and recompress it using a different
@ -224,18 +224,17 @@ find that it's much faster with zstd.
### Block, Schema and Metadata Compression ### Block, Schema and Metadata Compression
DwarFS filesystems consist of three distinct parts of data. Many blocks, DwarFS filesystems consist of three distinct parts of data: A potentially
which store actual file data and are decompressed on demand, as well as large number of blocks, which store actual file data and are decompressed
one schema and one metadata section. The schema is tiny, typically less on demand, as well as one schema and one metadata section. The schema is
than 1000 bytes, and holds the details for how to interpret the metadata. tiny, typically less than 1000 bytes, and holds the details for how to
The schema needs to be read into memory once and is subsequently never interpret the metadata. The schema needs to be read into memory once and
accessed again. The metadata itself is usually not compressed, although is subsequently never accessed again. The metadata itself is compressed
it can be if you want to squeeze a few more kilobytes out of the file by default, but it doesn't have to be. Actually, if you drop the compression
system. If it is compressed, it will be fully decompressed into memory. level from 7 (the default) to 6, the only difference is that the metadata
Otherwise, the metadata part of the file will simply be mapped into memory. is left uncompressed. This can be useful if mounting speed of the file
The main difference is that compressed metadata, which being smaller, will system is important, as the uncompressed metadata part of the file can
potentially consume more memory and it will definitely take longer to then simply be mapped into memory.
mount the filesystem initially.
## AUTHOR ## AUTHOR