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![]() The redundant_metadata setting in ZFS allows users to trade resilience for performance and space savings. This applies to all data and metadata blocks in zfs, with one exception: gang blocks. Gang blocks currently just take the copies property of the IO being ganged and, if it's 1, sets it to 2. This means that we always make at least two copies of a gang header, which is good for resilience. However, if the users care more about performance than resilience, their gang blocks will be even more of a penalty than usual. We add logic to calculate the number of gang headers copies directly, and store it as a separate IO property. This is stored in the IO properties and not calculated when we decide to gang because by that point we may not have easy access to the relevant information about what kind of block is being stored. We also check the redundant_metadata property when doing so, and use that to decide whether to store an extra copy of the gang headers, compared to the underlying blocks. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Signed-off-by: Paul Dagnelie <paul.dagnelie@klarasystems.com> Co-authored-by: Paul Dagnelie <paul.dagnelie@klarasystems.com> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Tony Hutter <hutter2@llnl.gov> |
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Makefile.am | ||
zdb_il.c | ||
zdb.c | ||
zdb.h |