Disk Test & Health Monitoring

$ jot - 900000 100000 -50000 | xargsi -t badblocks -c {} -nv /dev/hda
[...]
badblocks -c 150000 -nv /dev/hda
badblocks: Cannot allocate memory while allocating buffers
badblocks -c 100000 -nv /dev/hda
Initializing random test data
Checking for bad blocks in non-destructive read-write mode
[...]

By default only a non-destructive read-only test is done.

-n     Use  non-destructive  read-write  mode.

-w     Use write-mode test. With this option, badblocks scans  for  bad
       blocks  by  writing  some  patterns  (0xaa, 0x55, 0xff, 0x00) on
       every block of the device, reading every block and comparing the
       contents.   This  option may not be combined with the -n option,
       as they are mutually exclusive.

Badblocks needs memory proportional to the number of blocks tested at once, in read-only mode, proportional to twice that number in read-write mode (NB, might not be true. I noticed that the memory requirement is constant, as in e2fsprogs-1.27-9. Tong), and proportional to three times that number in non-destructive read-write mode.

If you set the number-of-blocks parameter (-c) to too high a value, badblocks will exit almost immediately with an out-of-memory error "while allocating buffers" in non-destructive read-write mode.

If you set it too low, however, for a non-destructive-write-mode test, then it's possble for questionable blocks on an unreliable hard drive to be hidden by the effects of the hard disk track buffer.

-p num_passes
       Repeat  scanning  the disk until there are no new blocks discov-
       ered in num_passes consecutive scans of the disk.  Default is 0,
       meaning badblocks will exit after the first pass.

-v     Verbose mode.