Re: Limitations of rsnapshot-style backups (Was: Re: lazy old guy asks question)
>> On Mon 01 Sep 2025 at 16:15:39 (-0400), David Christensen wrote:
> a. Set the ZFS backup file system property "dedup". This will enable
> block-level de-duplication, which can de-duplicate data more than hard
> links alone.
This option eats RAM like candy, so make sure you have plenty.
> b. Set the ZFS backup file system property "compression".
If you have large backup files, you can save more space by using "gzip"
for compression. On my backup box, this is for highly-compressible data
like large (1-3Gb) text-formatted logs:
Method Best Compression Ratio
-------------------------------
gzip 8.07x
lz4 5.83x
"gzip" takes slightly longer to store a big file, but I don't notice
any real delays when reading it. And I'm not patient.
> 3. zfs-diff(8) -- for example, to determine the backed up directories
> and files whose metadata and/or data have changed between two snapshots:
https://bezoar.org/src/zfs-snapshots/ describes using this for faster
incremental backups, even on spinning rust.
--
Karl Vogel I don't speak for anyone but myself
Happy Sysadmin day. My dog took a dump in my bedroom
this morning to celebrate. --Reddit, 25 Jul 2025
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