Subject: Question about raw vs. block devices
To: None <current-users@NetBSD.ORG>
From: Dave Huang <>
List: current-users
Date: 02/23/1997 16:38:43
What exactly is the difference between, say /dev/rcd0a and /dev/cd0a? I
notice that if I dd from rcd0a, I have to set bs=2k, while I can use the
default 512 byte blocksize with cd0a. However, "dd if=/dev/rcd0a bs=2k"
and "dd if=/dev/cd0a" don't return the same data. Even "dd if=/dev/cd0a
bs=2k" gives different data than reading from the raw device, which seems
rather strange to me...

I ask because I compiled the "hfsutils" package, since I wanted to read
Mac HFS CDs on my pentium, but hfsutils always reads 512-byte blocks.
Using rcd0a fails since it's not reading a 2k sectore, and using cd0a
fails because it's not getting back the right data.

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