[CentOS] Order of sata/sas raid cards

Fri Aug 24 15:04:31 UTC 2012
m.roth at 5-cent.us <m.roth at 5-cent.us>

Les Mikesell wrote:
> On Fri, Aug 24, 2012 at 9:24 AM,  <m.roth at 5-cent.us> wrote:
>> > I'll step into this again: let's look at the context.
>> 1. a drive's failed. No conflict.
>> 2. a server's failed, and you want something off one of its disks:
>>      a) you put it in a hot swap bay, and aren't rebooting the server -
>>            you are going to be manually mounting it, so no conflict
>>      b) you need to replace the server in -10 sec: you throw the
>> drive(s)
>>            into a standby box, and either
>>           i. it's got partitions labelled /boot and /; fine, you
>>               *want* it to use those
>>           ii. you want a drive from another disk on that failed
>>                system: no problem - see 2.a.
>>      c) you have a system without hot swap bays, and you install
>>           the drive from the failed system, and then you do have to
>>           power up; this is the only case I can think of, off the
>>           top of my head where you have a collision. In this case,
>>           you need linux rescue, and relabel.
>> So, where's the big issue with std. labels?
> You power down, add some disks that you want to re-use.  Maybe even
> add a controller.  Just because a bay looks like you can hot-swap
> doesn't mean it is a good idea if you don't have to.   You boot up.

Okayyyy... We differ, here - I've come to adore hot-swap bays, and hate
having to take a system apart to add another drive.

Reused disks - I reformat them, usually in a hot swap bay.

Of course, I *do* have some additional concerns - I have to worry about
PII and HIPAA data that may, *possibly*, be on the drives.

> When the label scheme was first rolled out, the machine wouldn't boot
> if it found a duplicate.   Now it will pick one.  Possibly the wrong
> one.  As you might when you do a rescue boot for the relabel since you
> won't know which controller is detected first.

But you can do a rescue, mount, and look at what's on what the controller