[CentOS] Building a Back Blaze style POD

Sun May 8 20:23:23 UTC 2011
John R Pierce <pierce at hogranch.com>

On 05/08/11 1:11 PM, John R Pierce wrote:
> On 05/08/11 1:03 PM, Jason Pyeron wrote:
>> If you can use less drives, this would be more cost effective (time building&
>> time fixing)
>> http://www.newegg.com/Product/Product.aspx?Item=N82E16811219038  [400$]
> multiple reports online indicate that norco case is very flimsy and
> poorly made.

ooops, hit send too fast.

also, that Norco case appears to require a seperate SATA channel for 
each of the 24 drives while the supermicro case has SAS2 multiplexed 
backplanes that will let you put 24 SATA drives on a single 4 channel 
SAS port, or 24 dual ported SAS drives on 2 4 channel SAS ports (using 
MPIO)... these backplanes have SES controllers on them for power and 
hotswap management (the SES functionality is integrated into the LSI SAS 
multiplexor chip used).   note that SAS supports N:M multiplexing where 
any one of the N controller channels can address any of the M 
devices.... plain SATA only supports 1:M simple expanders

And, a significant problem in large drive arrays is mechanical 
resonance.... you get an array of 24 or whatever disks all being 
hammered at once in a RAID environment, and the mechanical vibrations 
can cause interactions which can increase the error rate, this is 
greatly compounded by a flimsy chassis.