OpenZFS Is Still Battling A Data Corruption Issue

Last week OpenZFS 2.2.1 was released with a reported fix for a data corruption issue that was initially blamed as being a block cloning bug for a new feature introduced in the v2.2 release. Well, it turns out that the block cloning feature isn't the root cause and that v2.2.1 is still prone to data corruption and pre-v2.2 releases are also vulnerable to this file-system data corruption issue.

Over the US holiday weekend it became more clear that this OpenZFS data corruption bug isn't isolated to just the v2.2 release -- older versions are also susceptible -- and that v2.2.1 is still prone to possible data corruption.

The good news at least is that data corruption in real-world scenarios is believed to be limited but with some scripting help the corruption can be reproduced. It's also now believed that the OpenZFS 2.2 block cloning feature just makes encountering the problem more likely.

The FreeBSD project today issued an advisory over this OpenZFS data corruption issue. As a workaround they recommend setting "sysctl vfs.zfs.dmu_offset_next_sync=0" to "drastically reduce the likelihood" of encountering the problem.

This pull request is pending that hopefully takes care of the OpenZFS data corruption issue.

Stay tuned for more details and hopefully this matter will be buttoned up soon with a new OpenZFS point release to properly fix this data corruption issue.