> -----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 -- Rayford Johnson RHCA Complex Systems Technical Support Consultant Enterprise Expert Center Dell Services http://www.dell.com/services/ [email protected] 1-800-945-3355 x946-4954 Wed-Sat 08:00-19:00 CT Key ID: 0xC7158479 FP: FF8D F2EE 067E 40BD E179 D69D 69C0 9F37 C715 8479 _______________________________________________ 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
