KDiskMark is an HDD and SSD benchmark tool with a very friendly graphical user interface.
Te hoê taata nenei i te mau tuhaa i faataa - ê - na - hia
GParted is a free partition editor for graphically managing your disk partitions.
GNOME Disks
GNOME Disks, gnome-disk-image-mounter and gsd-disk-utility-notify are libraries and applications for dealing with storage devices.
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Disk Usage Analyzer is a graphical application to analyse disk usage in any Gnome environment.