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
– The D Merged, Commented Jan 9, 2014 at 8:02

Vasily Tarasov · Accepted Answer · 2014-09-29 18:45:46Z

14

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

answered Sep 29, 2014 at 18:45

Vasily Tarasov

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Comments

BiG_NoBoDy · Accepted Answer · 2017-11-17 07:54:30Z

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, 2017 at 7:54

BiG_NoBoDy

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