# Disks
Linux disk (HDD, SDD, etc) tips.

# Health testing
Check SMART capable disks with `smartctl -A /dev/sda`. Look for total bytes written, power on hours, integrity errors.

See Douglas Gilbert's article https://sg.danny.cz/scsi/smartmontools_scsi.html on what is SMART (and what it's not), smartctl as well as info about SCSI/ATA/PATA/SATA.


# Speed testing
Check USB speeds with `lsusb -t`

Test disk write speeds with dd: ``dd if=/dev/zero of=benchmark.img bs=1G count=2 status=progress``


# Tips
Safe unmount with `sudo udisksctl power-off -b /dev/sda`

Free up space reserved for the root account with ``tune2fs -m 0`` [``/dev/sdXY``.](file:///dev/sdXY.) This is useful for a storage-only drive.



# Special block devices
`/dev/urandom`: non-blocking random bytes
`/dev/random`: legacy, blocking if not enough entropy (early boot)