Namaste Misc,

ASSUMPTION
Consider two disks sd0 and sd1 assembled into sd2 with RAID 1C as the
discipline.

QUESTION
Which of the following is the correct way to write random data for the
RAID 1C discipline during installation?

1) # dd if=/dev/urandom bs=1m 2>dd.result | tee /dev/rsd0c > /dev/rsd1c
In other words, writing random data to the disk before initializing the
disk (fdisk), creating the partitions (disklabel) and assembling the
softraid device sd2 (bioctl).

2) # dd if=/dev/urandom of=/dev/rsd2c bs=1m
In other words, writing random data to the assembled disk sd2.

3) Both of the above.

CONTEXT
>From the Full Disk Encryption section of Disk FAQ [1]:
"
...
You may want to write random data to the drive first with something like
the following:

# dd if=/dev/urandom of=/dev/rsd0c bs=1m

This can be a very time-consuming process, depending on the speed of
your CPU and disk, as well as the size of the disk. If you don't write
random data to the whole device, it may be possible for an adversary to
deduce how much space is actually being used.
...
"

>From my limited understanding, this concept of writing random data
is applicable for the RAID 1C discipline as well.

However, the guidance on this is missing for RAID 1C discipline.

Hence the question.

Dhanyavaad,
Dharma Artha Kama Moksha

[1] - https://www.openbsd.org/faq/faq14.html#softraidFDE

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