7

While testing a problem LUN for read errors, I encountered the following problem:

find /mnt/problem_lun/ -type f -print -exec dd if={} of=/dev/null bs=8k \;
...
/mnt/problem_lun/a_file
dd: writing `/dev/null': File too large
33619977+0 records in
33619976+0 records out
275414843392 bytes (275 GB) copied, 804.171 s, 342 MB/s

IBM hardware, RHEL 6.6

Who's the culprit, provided this particular file could be read without any errors?

Zogratz
  • 79

1 Answers1

13

It looks like your /dev/null may have been deleted at some point so when you started writing to it you are writing to a plain file rather then the character special null device.

You an confirm this by looking at the output of ls

$ ls -l /dev/null
crw-rw-rw-. 1 root root 1, 3 Sep 28 08:11 /dev/null

If I'm right then you won't see a character special device. You can repair this by first deleting the file you created and then running 

MAKEDEV std

which should work on EL6 or 

mknod -m 666 /dev/null c 1 3
user9517
  • 116,228