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ZFS, OpenBSD, FreeBSD, GhostBSD and More
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Mariusz Zaborski ☛ Don't Make ZFS Re-Read What It Just Read
I have already mentioned one of my improvements to scrub in an earlier post, Teaching ZFS about time. In that post I also claimed that scrub can be expensive, and that we were looking for ways to limit the amount of data we actually want to scrub. A scrub on a multi-petabyte pool can run for days, and some of us want a smaller, easier check that everything is still going right.
For people who scrub on a schedule - say once a month - most of those days are spent re-reading blocks that the previous scrub already verified, and that nothing has touched since. Of course, other bad things can happen, like physical degradation of a disk, but sometimes we can assume that "the disks were perfectly happy then, and the blocks are not rabbits - they have not hopped away". Under that assumption, the only blocks worth re-reading are the ones written since the last scrub finished.
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Audiocasts/Shows
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The BSD Now Podcast ☛ BSD Now 665: 60 Puffies
OpenBSD 7.9, Critical Infrastructure in FreeBSD, GhostBSD Finance report, Solaris 11.4 updates, and more...
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