dd fail to write to tmpfs

Question

I'd like to measure tmpfs performance by using dd. But it fail, like below:

# dd if=/dev/zero of=/tmp/128M bs=4M count=32 oflag=direct  
dd: failed to open ‘/tmp/128M’: Invalid argument

Any help?

What does "file /tmp/128M" give you? looks like the file do not exist. Maybe you do not have permissions? Try sudo — The D Merged, Jan 09 '14 at 08:02

score 14 · Answer 1 · answered Sep 29 '14 at 18:45

14

tmpfs does not support direct I/O and returns -EINVAL.

answered Sep 29 '14 at 18:45

Vasily Tarasov

score 5 · Answer 2 · answered Nov 17 '17 at 07:54

5

Vasily Tarasov solution worked with NFS too. I had:

dd if=/dev/urandom of=TEST.200GB iflag=direct bs=1M count=204800
dd: failed to open ‘/dev/urandom’: Invalid argument

then I have removed iflag=direct and it worked

answered Nov 17 '17 at 07:54

BiG_NoBoDy

2 Answers2