In OpenZFS and Btrfs, everyone was just guessing

Re:In OpenZFS and Btrfs, everyone was just guessing by yakubin on Friday December 01, 2023 @05:44PM (#38493590)

> disabling the writing of 'last accessed' timestamps

atime is the most useless filesystem feature I’ve heard of. But on most Unix-like systems it’s enabled by default and the main thing it does is turn reads into writes, degrading performance. All the while ctime isn’t a standard Unix filesystem feature. And ctime to me always seemed infinitely more useful (and cheaper!) than atime.

</rant>

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Re:In OpenZFS and Btrfs, everyone was just guessing by mischief6 on Saturday December 02, 2023 @01:22AM (#38496423)

while it is unfortunate it requires a write, it is useful in some cases. for example, finding old objects in a cache, or today i used it to find out what firmware my kernel is loading by checking atime of /lib/firmware.

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Re:In OpenZFS and Btrfs, everyone was just guessing by mike_hock on Saturday December 02, 2023 @05:42AM (#38497625)

So it's useful as a debugging feature that you might want to briefly turn on once every decade.

Finding old objects in a cache is an issue specific to caches and should be implemented there.

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Re:In OpenZFS and Btrfs, everyone was just guessing by cromka on Saturday December 02, 2023 @06:32AM (#38497860)

For the latter you could enable it, reboot and get the same information right away, then disable it?

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Re:In OpenZFS and Btrfs, everyone was just guessing by mischief6 on Saturday December 02, 2023 @12:30PM (#38500181)

i did not see a clear list of all firmware files read by the kernel in dmesg, so the find/atime trick worked well.

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Re:In OpenZFS and Btrfs, everyone was just guessing by yencabulator on Wednesday December 06, 2023 @11:50AM (#38546338)

relatime has been the Linux default since 2009. It makes that be one write per 24 hours.

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