How to write a pattern to a device to use it with badblocks with -t test_pattern option

Question

I recently bought a 4TB hard disk and I want to do a read-write badblocks test on this before I start using it. Since running badblocks with -w option would take ages for 4TB, I've thought to first write a pattern on the disk and then use the -t option to read that pattern through badblocks, completing it in hours rather than in days.

The problem is that I couldn't understand how the -t option of badblocks works and I got no search results when searching the web for an example of using badblocks with -t option. From man page, test pattern is a numeric value between 0 and ULONG_MAX-1 (I'm making a wild guess that ULONG_MAX is 2^32), but I'm not sure how to provide the pattern (decimal? hexadecimal? binary? ASCII string with length < 2^(32/8)?). And is the pattern size related to block size?

The other part of the problem is to write a script to fill the hard disk with the pattern. I can write a Ruby script to do that, but a one liner bash command piped through pv would be nice!

Answer 1

Letting badblocks write the pattern in the first place should be no slower than writing it any other way. Especially if you use the -b block-size and -c blocks-at-once options so it doesn't do small reads/writes.

This example overwrites the disk with "random" pattern in 1MiB blocks:

badblocks -v -w -t random -b 4096 -c 256 /dev/thedisk

If there is a problem with speed, it should have some other cause...

Answer 2

Writing a pattern with one tool and reading it with badblocks is not going to be much faster than running badblocks with a single pattern, I imagine.

The pattern needs to be specified in hex, at least that's what I understand from this:
badblocks -t 0x55 -w [...]

Source: https://github.com/autotest/ctcs/blob/master/runin/destructiveblocktstrnd

Answer 3

So after some more research, I came up with a way to utilise the -t option of badblocks (but you should prefer frostschutz's answer (I somehow missed to notice the -c option while asking this question)).

Write 42 all over the hard disk.

yes 4 | tr '\n' 2 | pv -pterb -s 4000G > /dev/sdx

Verify through badblocks

badblocks -vs -t 0x3432 /dev/sdx