[pve-devel] [PATCH docs] add section about backup compression algorithms

[Aaron Lauterer]

Some nits inline.

either in s/x/y/ syntax or just a rewrite of a sentence.

On 5/7/20 2:42 PM, Alwin Antreich wrote:
> as a short description about the different algorithms in use by vzdump.
> 
> Signed-off-by: Alwin Antreich <a.antreich at proxmox.com>
> ---
>   vzdump.adoc | 36 +++++++++++++++++++++++++++++++++++-
>   1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/vzdump.adoc b/vzdump.adoc
> index 404ad09..3fd9ca9 100644
> --- a/vzdump.adoc
> +++ b/vzdump.adoc
> @@ -147,6 +147,40 @@ That way it is possible to store several backup in the same
>   directory. The parameter `maxfiles` can be used to specify the
>   maximum number of backups to keep.
>   
> +Backup File Compression
> +-----------------------
> +
> +The backup file can be compressed with the following algorithms: lzo
s/with/with one of/

Would it be helpful if we would make the algos a bit stand out? e.G. 
`lzo` or 'lzo'. Whatever fits better into the text flow.

> +footnote:[Lempel–Ziv–Oberhumer a lossless data compression algorithm
> +https://en.wikipedia.org/wiki/Lempel-Ziv-Oberhumer], gzip footnote:[gzip -
> +based on the DEFLATE algorithm https://en.wikipedia.org/wiki/Gzip] or zstd
> +footnote:[Zstandard a lossless data compression algorithm
> +https://en.wikipedia.org/wiki/Zstandard].
> +
> +Currently, Zstandard (zstd) is the fastest of these three algorithms. It also
> +has the advantage of being multi-threaded. While lzo and gzip are not. In
> +contrast to zstd, lzop and gzip are more widely used and are often installed by
> +default.

Multi-threading is another advantage of zstd over lzo and gzip. Lzo and 
gzip are more widely used and often installed by default.

> +
> +You can install pigz footnote:[pigz - parallel implementation of gzip
> +https://zlib.net/pigz/] as a drop-in replacement for gzip to provide better
> +performance due to multi-threading. For pigz & zstd, the amount of
> +threads/cores can be adjusted, see the
> +xref:vzdump_configuration[configuration options] below.
> +
> +Through the backup file ending, you can usually determine what compression
> +format was used during backup.

The extension of the backup file name can usually be used to determine 
which compression algorithm has been used to create the backup.

> +
> +|===
> +|.zst | Zstandard (zstd) compression
> +|.gz or .tgz | gzip compression
> +|.lzo | lzo compression
> +|===
> +
> +If the backup file doesn't end with one of the above file extensions, then the
s/backup file/backup file name/
s/then the//

> +backup was not compressed by vzdump.
s/backup/it/

> +
> +
>   [[vzdump_restore]]
>   Restore
>   -------
> @@ -203,7 +237,7 @@ per configured storage, this can be done with:
>   # pvesm set STORAGEID --bwlimit restore=KIBs
>   ----
>   
> -
> +[[vzdump_configuration]]
>   Configuration
>   -------------
>   
>