[CentOS] Software RAID1 with CentOS-6.2

Wed Feb 29 19:46:08 UTC 2012
Miguel Medalha <miguelmedalha at sapo.pt>

A few months ago I had an enormous amount of grief trying to understand 
why a RAID array in a new server kept getting corrupted and suddenly 
changing configuration. After a lot of despair and head scratching it 
turned out to be the SATA cables. This was a rack server from Asus with 
a SATA backplane. The cables, made by Foxconn, came pre-installed.

After I replaced the SATA cables with new ones, all problems were gone 
and the array is now rock solid.

Many SATA cables on the market are pieces of junk either incapable of 
coping with the high frequencies involved in SATA 3Gb/s or 6Gb/s or 
their connector are made of bad quality plastics unable to keep the 
necessary pressure on the contacts.

I had already found this problem with desktop machines, I simply 
wouldn't believe that such a class of hardware would exhibit it also.

So, I would advise you to replace the SATA cables with good quality ones.

As an additional information, I quote from the Caviar Black range datasheet:

"Desktop / Consumer RAID Environments - WD Caviar Black Hard Drives are 
tested and recommended for use in consumer-type RAID applications 
(RAID-0 /RAID-1).
- Business Critical RAID Environments – WD Caviar Black Hard Drives are 
not recommended for and are not warranted for use in RAID environments 
utilizing Enterprise HBAs and/or expanders and in multi-bay chassis, as 
they are not designed for, nor tested in, these specific types of RAID 
applications. For all Business Critical RAID applications, please 
consider WD’s Enterprise Hard Drives that are specifically designed with 
RAID-specific, time-limited error recovery (TLER), are tested 
extensively in 24x7 RAID applications, and include features like 
enhanced RAFF technology and thermal extended burn-in testing."