dmose
Bronze

Re: SAS 5/IR Performance

I disagree.  The SAS *IS* a hardware raid device.  The OS is not doing the raid management.  The problem is the drivers and write-caching.  Write caching is disabled because these cheapy raid cards don't have battery AND RAM on them..thus they are set in write-through mode which is brutually slow. There doesn't seem to be an easy way to enable this write-caching I currently have a ticket open hoping that an engineer at dell will resolve this issue.
 
What the user is experience is a combination of both the write-through slowness AND windows 2003 starting to page after a few GB of file transfer
 
Here is a good thread of UNIX guys discovering the issue, and fixing it by enabling Write-Caching:
 
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