[rescue] playing with the new E250 ... disk performance vs. old PeeCee

[Joshua Boyd]

On Mon, Dec 18, 2006 at 11:41:21AM -0500, Magnus wrote:

> I think someone earlier in the thread suggested that the SCSI controller 
> in the E250 was good for up to 40MB/sec.  I am looking at Sun's page on 
> the E250 at http://www.sun.com/servers/entry/250/index.html which 
> describes the controller as "Ultra SCSI" and at 
> http://www.storagereview.com/guide2000/ref/hdd/if/scsi/modesUltra.html 
> which describes "Ultra SCSI" as "20 MHz bus speed; 20 MB/s" so I am 
> indeed maxing out the controller.

Plain Ultra SCSI is indeed 20MB/s.  However, the E250 is really
UltraWide SCSI. 

I get 18MB/s writes between two mirror'd disks in the internal cage.  I
get more than 30MB/s reads on the same mirror set.  
 
> There is a great summary at 
> http://www.storagereview.com/guide2000/ref/hdd/if/scsi/summary.html of 
> the myriad flavors of SCSI. I knew that SCSI had gotten convoluted over 
> the years but now I'm going to need to go back and see just what 
> standards my drives are capable of and try to find a decent match.

I don't recall what you said your drives were, but they are probably U2W
(80MB/s bus speed) or U160 (160MB/s bus speed).  However, you also
should look at the actual drive speed.  For instance, if you have two
U320 drives that only do 50MB/s each, then you loose nothing by putting
them on a U160 controller, or putting them on seperate channels of a U2W 
controller. 

-- 
Joshua D. Boyd
jdboyd at jdboyd.net
http://www.jdboyd.net/
http://www.joshuaboyd.org/