On Thu, 2009-07-16 at 07:56 -0500, [email protected] wrote: > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf > > Of Matthew Lenz > > Sent: Thursday, July 16, 2009 7:44 AM > > To: linux-poweredge-Lists > > Subject: Re: perc 4 write performance after upgrading to debian lenny > > > > On Mon, 2009-07-13 at 11:04 -0500, Matthew Lenz wrote: > > > [ 8.791408] sd 0:2:0:0: [sda] Write Protect is off > > > [ 8.791412] sd 0:2:0:0: [sda] Mode Sense: 00 00 00 00 > > > [ 8.791432] sd 0:2:0:0: [sda] Asking for cache data failed > > > [ 8.791480] sd 0:2:0:0: [sda] Assuming drive cache: > > write through > > > > > anyone able to provide some insight on this one? its really hosing > > things up :( > > > > This message displays when the Linux SCSI Mid Layer asks for physical > disk cache settings. Because the PERC firmware manages the virtual disk > cache settings on a per controller and a per virtual disk basis, the > firmware does not respond to this command. Thus, the Linux SCSI Mid > Layer assumes that the virtual disk's cache policy is write through > since it is the safer choice. > > Except for this message, there is no side effect to this behavior. The > cache policy of the virtual disk and the I/O throughput are not affected > by this message. The cache policy settings for the PERC remain the > settings chosen for a given virtual disk. > > http://lists.us.dell.com/fom-serve/cache/110.html
Thanks so much for pointing that out. Any ideas on how to proceed diagnosing the poor performance? Is there a benchmark I can post to the list for the boxes to help accurately determine what exactly my read / write performance is? _______________________________________________ Linux-PowerEdge mailing list [email protected] https://lists.us.dell.com/mailman/listinfo/linux-poweredge Please read the FAQ at http://lists.us.dell.com/faq
