Bug#398310: don't assemble all arrays on install

[dean gaudet]

Package: mdadm
Version: 2.5.5-1
Severity: grave

it's dangerous to generate an mdadm.conf and start running arrays 
automatically at install time!  i nearly got bit by this.

i marked this grave because there's a potential for data loss with the 
current install scripts.

i had 4 disks which i had experimented with sw raid10 on a few months 
back... i never zeroed the superblocks.  i ended up putting them into 
production in a 3ware hw raid10.  today the 3ware freaked out... and i put 
the disks into another box to attempt forensics and to try constructing 
*read-only* software arrays to see if i could recover the data.

when i did "apt-get install mdadm" it found the old superblocks from my 
experiments a few months ago... and tried to start the array!

fortunately i had issued "blockdev --setro /dev/sd[defg]" prior to doing 
any of this, so the block layer saved my ass.

otherwise mdadm would have happily screwed around with the data at the end 
of the disks... and *even worse* might have decided recovery was necessary 
and really screwed things up!

it's *bad* to autostart all discovered arrays.  it's unfortunate enough 
that you've decided to make initrds start all arrays by default... but at 
least this install-time autodiscover and start everything should be 
optional.

at a minimum i think there should be a dialog "attempt to autodiscover all 
arrays and start them?".  even better would be a second step "i found the 
following arrays, which ones should i start?"

-dean

p.s. regardless of this complaint, i'm totally happy with the newer 
initramfs which handles renames more gracefully... and with the monthly 
checkarray default.  thanks!