On 04/20/2011 05:43 PM, paul simpson wrote: > many thanks for sharing guys. an informative read indeed! > > i've 4x dells - each running 12 drives on PERC 600. was dissapointed to > hear they're so bad! we never got round to doing intensive tests this > in depth. 12x2T WD RE4 (sata) is giving me ~600Mb/s write on the bare > filesystem. joe, does that tally with your expectations for 12 SATA > drives running RAID6? (i'd put more faith in your gut reaction than our > last tests...) ;) Hmmm ... I always put faith in the measurements ... Ok, 600MB/s for 12 drives seems low, but they are WD drives (which is another long subject for us). This means you are getting about 60 MB/s per drive write on the bare file system on drives that are at least (in theory) able to get (nearly) double that. This is in line with what I expect from these units, towards the higher end of the range (was this direct or cached IO BTW). Most of our customers never see more than about 300-450 MB/s out of their PERCs with direct IO (actual performance measurement). -- Joseph Landman, Ph.D Founder and CEO Scalable Informatics Inc. email: landman at scalableinformatics.com web : http://scalableinformatics.com http://scalableinformatics.com/sicluster phone: +1 734 786 8423 x121 fax : +1 866 888 3112 cell : +1 734 612 4615
