This test reflects our limited experience of imitating a power outage, to see how a filesystem can handle it. Of course, we should have conducted more detailed exercises with storage devices handling high I/O with solid uptime figures. Still, despite the fact that we only got a rough impression of the filesystems’ reliability, the test method was highly practical.
For each of the five filesystems, we started copying a 7GB dataset on to the external SATA-III SSD and at some point unplugged it, reconnected and checked whether we could access the already copied data. XFS, Ext4 and NTFS handled the situation very well. After several drive disconnections for each filesystem, there were eventually errors caused by the metadata not being written on the drive, but that was expected. Each of these three filesystems has repair utilities that fixed the errors.