[CentOS] Race condition with mdadm at boot

Chuck Munro chuckm at seafoam.net
Sat Mar 12 19:35:43 UTC 2011

On 03/12/2011 09:00 AM, compdoc wrote:

>> >On the particular Supermicro motherboard I'm using, there is a very
>> >long delay (10 or 15 sec) between power-on and initiation of visible
>> >BIOS activity, so all disk drives have ample time to spin up and stabilize.
> Yeah, I have used Supermicro in the past and they had the same long pause
> when you turn them on. Good boards, except I had one die recently.
> I was wondering how many drives total, and how many watts the PSU is?
> Also, is the controller's firmware up to date?
I agree, Supermicro does design good boards, with a lot of server-grade 
features that consumer boards lack.  Not cheap, but worth the money.  I 
assume the long power-on pause is due to the BIOS silently checking RAM, 
with the side effect of giving the disks ample time to spin up.

I have a total of 15 drives.  Three of them are fast 2-1/2" drives used 
for the host OS filesystems, running on the ICH-10 SATA controller. No 
problem at all with those.

The other 12 drives are 2TB WD Caviar Black series.  6 are connected to 
the on-board 8-port LSI 1068E chip, and 6 divided equally between 2 
Tempo 'Sonnet' 4-port PCIe cards (Marvell chips).  All drives have the 
same 8 partitions each.

All drives have the same 8-partition configuration.  The LSI controller 
supports 8 RAID-6 arrays using 5 active drives plus a hot spare.  The 
Tempo controllers support the same arrangement using the other 6 drives.

The firmware on everything is up to date.

Other than the annoying failure to bind 1 or 2 random partitions on the 
last drive in each group of 6, the performance of this configuration is 
quite good.  I still have the 'scsi_mod.scan=sync' kernel parameter in 
place, so there may be some other cause of the failure to bind some of 
the partitions.  FWIW, in more than 10 system boots, there has never 
been any consistent pattern to these failures.


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