[CentOS] [HW] Do the HDD cages in rack mount chassis indicate visual/audio HDD failure?

[Les Mikesell]

On Tue, Oct 18, 2011 at 10:11 AM, Arun Khan <knura9 at gmail.com> wrote:
>
>>> I would appreciate clarification on the following:
>>
>>> (a) Indicate disk failure. LED lights up and/or audio alarm?
>>> (b) The failed HDD can be swapped.
>>
>> Don't rely on the LED going on. I mark all my hot swap disks with
>> labels with their serial number. This label is visible from the
>> outside without removing the HD.
>> That way, I can double check that I remove the faulty disk.
>> Pulling the wrong disk is the last thing you want to risk in a RAID
>> setup. Relying on a fault LED is close to that.
>> Also make a list of the HD serial numbers and their position within
>> the RAID in time. Store that in a safe place.
>
> Thanks for these very helpful suggestions - good admin practice.
>
>> I pulled ONCE the wrong disk out of a Raid5 array. :-(
>> You know what that means?
>
> You mean, it is not OK to pull out a "functioning" disk?  Pulling one
> disk out of RAID 5 should be OK.  Am I missing something?

Usually you would be swapping drives to repair an already-broken raid.
 Unless you have a hot spare and the raid has already rebuilt on it,
pulling a working disk will take a 2nd drive out of the failed raid5
and kill it.

-- 
   Les Mikesell
    lesmikesell at gmail.com