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Comment by wereHamster | Hacker News Reader

A loooong time age (OpenSolaris days) I had a system that had corrupted its zfs. No fsck was available because the developers claimed (maybe still do) that it's unnecessary.

I had to poke around the raw device (with dd and such) to restore the primary superblock with one of the copies (that zfs keeps in different locations on the device). So clearly the zfs devs thought about the possibility of a corrupt superblock, but didn't feel the need to provide a tool to compare the superblocks and restore one from the other copies. That was the point when I stopped trusting zfs.

Such arrogance…

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> So clearly the zfs devs thought about the possibility of a corrupt superblock, but didn't feel the need to provide a tool to compare the superblocks and restore one from the other copies.

This mailing list post from 2008 talks about using zdb(8) to mark mark certain uberblocks an invalid so another one would be used:

* https://zfs-discuss.opensolaris.narkive.com/Tx4FaUMv/need-he...

ZDB = ZFS debugger. It's been there since the original Solaris release of ZFS.

> That was the point when I stopped trusting zfs.

As opposed to trusting other file systems and volume managers, which do not have checksums, and so you wouldn't even know about the problem in the first place?

That's not using zdb to change anything - it's readonly, all the time. The person reached out and used dd on the disk to corrupt the copies of the uberblock with bad data so that ZFS would be forced to use the older ones (what zpool import -T does, basically, but doing it the hard way).

it's still the case even with now openzfs ? what do you trust now ?

That's a fine fit of pique - and I once had an awkward file on one of my zfs pools, about three pools ago - but how does it leave you better off, if you want what zfs offers?

> That's a fine fit of pique

So you're rejecting a story about a real bug because...?

> how does it leave you better off

That's a really mercenary way to look at learning about your tools.

But presumably they take smaller risks around zfs systems than they otherwise would.

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