[cisco-voip] 7825-I4 RAID and HDD strange behaviour or not !!!

[Ryan Ratliff]

In general Raid1 should allow the system to boot off of a single drive after a hardware failure.  That's what it is designed to do (afaik, I'm not a raid expert only play one on the internet).  On the 7825 array in my experience if you are doing lots of pulling drives, failing drives, upgrading firmware on drives, etc that's going to mean lots and lots of array resyncing.  If that resynchronization doesn't complete you don't have a redundant array.   The server won't be able to use the backup drive if the failure occurs when the array isn't optimal.

More inline below...

-Ryan
> 
> On Feb 14, 2012, at 10:43 AM, Sinisa Djokic wrote:
> 
> hi group..
>  
> does anybody have expertise on this matter..
> maybe wes or ryan have inside info..
>  
> we had a TAC case with failed HDD and problematic RAID controller in MCS-7825-I4 server running CUCM 7.1.5..
> the symptom happend when we shutdown the server in order to check what IBR FRU is on memory inside the server..we checked it and after that we powered up the server.. RAID controller reports DEGRADED state..cisco OS started to boot and in certain point it reported something like “ unsupported hardware......not for the production..without TAC support..bla..bla..bla )”..we opened the case..
> during the case we upgraded  all kinds of  firmware on server and  also find out that one HDD  failed..we replaced it and troubleshooted more..
> finally we got RMA for the server but have spotted very strange behavior on the new server as well ( we put in into lab to test it )..so, we’re thinking , is the following expected behaviour or there is a serious problem in cisco OS or IBM HW..
>  
> 1.       first of all we upgraded the HDD firmware on the new server we got from RMA to 3B06 ( it was with 3B05 ) having in mind CSCti52867 which we hitted earlier..after that we’installed CUCM 7.1.5..
At this point I'd guess that even 3B06 is old.  Make sure your drives are on the latest firmware, and make sure your array is up and completely stable before applying the update. If it's degraded when you try to patch it can miss one of the drives and leave it on old firmware.  If you hit CSCti52867 then you absolutely have to run the diskex...cop.sgn file (when the array is optimal) and really should rebuild the server.  Just upgrading the firmware is not sufficient to fix or prevent future outages once the drives have started failing due to this bug.

> 2.       when server is shut down and we pull out the right hard drive ( the one in BAY 1)..we power up the server..RAID controller detects one drive missing and reports DEGRADED state..cisco OS starts to boot and in certain point it reports again something like “ unsupported hardware......not for the production..without TAC support..bla..bla..bla )..
See the bug Wes pointed out.  This is not expected behavior.

> 3.       when we shut down the server again..and switch the scenario..we get back the right HDD in server ( BAY 1 ) and pull out the left HDD out ( BAY 0 )..when we power up the server..it doesn’t even  detect bootable device like there is no HDDs inside..
If the BIOS doesn't detect the drive you've got a hardware issue either with the array or the disk, period.  If the BIOS detects the drive but no OS is found then the drive most likely didn't get fully sync'd from a previous degraded state.

> 4.       so, when we shut down the server again..and get back both HDDs where they belong..power up the server..everythings works fine..of course, RAID is resynching..
Does it ever finish resyncing?  That can take hours and until it does the drive that is not in a good state is not redundant.  

> 5.       of course both HDDs used in server are in correct state and aren’t failed..
I wouldn't place bets on that just yet.

>  
> so, i’m a little bit confused, since it’s happening on 2 different servers..identical scenario..my RAID1 perception is in serious doubt..
> does this mean that if HDD failed during regular maintenance shutdown ( which we had in the first place ), RAID shouldn’t provide operational system?..
> to be honest , we didn’t have failed disk while server was  up and online so we couldn’t notice what’s going on in that situation..
> but the fact is, with the old server and with the new server, when we pull out one of the HDDs the system wouldn’t boot up properly..
> is this expected behaviour?..what’s the purpose of RAID1 then?..
> is RAID1 expected to cover just online HDD failure ( if so ) or it should work in every scenario?..
> any thoughts?..
>  
thanx..
 
 
regards..
 
Sinisa Djokic
System Engineer
CCIE #25996 Voice
 
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