Top 3 ZFS recovery software

ZFS filesystem is a very rare type of file system. Until recently, it was used only in "self-made" network storage devices. However, in recent years, more and more NAS manufacturers have chosen ZFS for their devices. So, for example, QNAP in 2021 released a line of devices running under the ZFS filesystem. Why does ZFS attract network device manufacturers? The answer to this question can be obtained by examining the advantages of this file system:

  • Checking and maintaining the integrity of the filesystem metadata;
  • High performance;
  • Minimization of data fragmentation;
  • The possibility to use different data block sizes for different tasks.

If the device running under ZFS breaks down, then the user has a really big problem, because, firstly, there are very few tools for ZFS data recovery, and secondly, even these data recovery tools work in very limited cases due to the complex organization of data storage on ZFS.

We have reviewed three data recovery tools that claim to be able to recover data from ZFS. For testing, we used disk images from TrueNAS. We have summarized the results in a table. Below the table, some comments will be provided.

Parametr Klennet ReclaiMe Pro UFS Explorer
Supported redundancy levels
raidz + + +
raid2z + + +
raid3z + + +
How many disks can be lost
raidz missing + + +
raidz2 missing + + +
raidz2 2 missing + + +
raidz3 missing + + +
raidz3 2 missing + + +
raidz3 3 missing + + -
Cases of data loss
Files deletion Incomplete Recovery Incomplete Recovery Incomplete Recovery
Deletion of DataSet (a network folder) Fully recovered (very long recovery time) Fully recovered Fully recovered (but it was inconvenient to search for files)
Volume deletion Fully recovered Fully recovered using Find ZFS option Not recovered (partition not found at startup)

As can be seen from the table, the recovery results for all three tools are approximately the same. In terms of functionality, UFS loses a little, since it does not provide the ability to restore raidz3 with 3 missing disks. And also, UFS Explorer did not cope with the task of recovering data from a deleted volume. As for the software interface, ReclaMe Pro is perhaps the most convenient and understandable.

It is impossible to give an estimate of the recovery time within our testing, because we did tests on small disk images, but even on such small images, Klennet was much slower than ReclaiMe Pro and UFS.

Anyway, if you need to recover the data from ZFS, most likely you will have to try all 3 tools to understand which one can give the best result.