[CentOS] CentOS Digest, Vol 81, Issue 12

Wed Oct 12 20:57:44 UTC 2011
CS <calsawyer at yahoo.co.uk>

> On 10/11/11 7:29 AM, Arun Khan wrote:
>>> that requires specific configuration to suit whatever drive interconnect
>>>> you have.
>> Does these bays have a connector (+ cable) that is connected to the
>> motherboard or RAID card to control the HDD LEDs in the bay?
>> (sorry if this appears basic but I have no experience with such hardware)
> typically, a server will have a SAS backplane which sas/sata drives hot 
> plug into, and 1 or more 4 channel SAS ports that plug into the host bus 
> adapter or raid controller.  this SAS backplane usually has a 'SES' 
> controller[*] embedded on it, which appears to the host as another SAS 
> device, and manages the LEDs.   If its a brand name server (hp, dell, 
> ibm, etc) using the vendor's raid cards, the LEDs all just work.    if 
> its whitebox stuff, with JBOD, getting the right failure LEDs to come on 
> may require some custom configuration.
> [*] SES supercedes the earlier SAF-TE design for the same functionality.
> -- 
> john r pierce                            N 37, W 122
> santa cruz ca                         mid-left coast

I'm guessing you want to be able to ID a failed drive visually and mdadm can make that a challenge.

A SATA backplane likely will have a signal bus connector (Suoermicro server backplanes do)  but onboard controllers probably won't supply the other end  Built servers definitely will as john points out.  Better hardware RAID HBAs probably shoild have the complimentary signal bus connector.  Make sure your system builder or supplier gets you the right cable bits - i'm pretty sure they're not universal.

- csawyer