Special failsafe is a feature that allows your special allocation class vdevs ('special' and 'dedup') to fail without losing any data. It works by automatically backing up all special data to the pool. This has the added benefit that you can safely create pools with non-matching alloc class redundancy (like a mirrored pool with a single special device). This behavior is controlled via two properties: 1. feature@special_failsafe - This feature flag enables the special failsafe subsystem. It prevents the backed-up pool from being imported read/write on an older version of ZFS that does not support special failsafe. 2. special_failsafe - This pool property is the main on/off switch to control special failsafe. If you want to use special failsafe simply turn it on either at creation time or with `zpool set` prior to adding a special alloc class device. After special device have been added, then you can either leave the property on or turn it off, but once it's off you can't turn it back on again. Note that special failsafe may create a performance penalty over pure alloc class writes due to the extra backup copy write to the pool. Alloc class reads should not be affected as they always read from DVA 0 first (the copy of the data on the special device). It can also inflate disk usage on dRAID pools. Closes: #15118 Signed-off-by: Tony Hutter <hutter2@llnl.gov> |
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README.md
OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.
Official Resources
- Documentation - for using and developing this repo
- ZoL Site - Linux release info & links
- Mailing lists
- OpenZFS site - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
Installation
Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.
Contribute & Develop
We have a separate document with contribution guidelines.
We have a Code of Conduct.
Release
OpenZFS is released under a CDDL license.
For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197
Supported Kernels
- The
META
file contains the officially recognized supported Linux kernel versions. - Supported FreeBSD versions are any supported branches and releases starting from 12.4-RELEASE.