Fixing minor disk naming issue when running read-only dd test.

[byrondover]

If this line is uncommented for a read-only dd test as is, I encounter a disk naming issue resembling the following:

$ sudo ./cluster-validation/pre-install/disk-test.sh
Unused disks:  /dev/sdi /dev/sdj /dev/sdk /dev/sdl /dev/sdd /dev/sdf /dev/sda /dev/sdb /dev/sde /dev/sdc /dev/sdg /dev/sdh
Scrutinize this list carefully!!
dd of=/dev/null if=/dev//dev/sdi iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdj iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdk iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdl iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdd iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdf iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sda iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdb iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sde iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdc iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdg iflag=direct bs=1M count=1000
dd of=/dev/null if=/dev//dev/sdh iflag=direct bs=1M count=1000

Since /dev is already prepended in your $disks variable, we don't need to prepend it again within the for loop.

[jbenninghoff]

Fixed in updated disk-test.sh which has -r option to run read-only (dd) tests.