From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: optimal io size / custom alignment Date: Thu, 18 Jun 2015 17:01:19 -0400 Message-ID: References: <20150615133154.GV1992@ws.net.home> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (Tom Yan's message of "Wed, 17 Jun 2015 17:49:51 +0800") Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tom Yan Cc: "Martin K. Petersen" , linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Karel Zak , util-linux-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-scsi@vger.kernel.org >>>>> "Tom" == Tom Yan writes: Tom> No I put it in the wrong way. What I meant was "sd vs md". For Tom> example, couldn't the scsi disk driver bind the value it reads from Tom> the VPD to another variable instead of "optimal i/o size", so that Tom> this value would be exclusively for RAID (and other virtual Tom> devices)? Who says that RAID is a virtual device? Hardware RAID controllers as well as SAS, iSCSI and Fibre Channel disk arrays all use the Block Limits VPD to communicate their preferred I/O size and alignment to us. As do enterprise disk drives. We deal with broken devices by blacklisting them. I suggest you try to find a way we can reliably identify your UAS devices. If there is a common pattern, we can entertain adding a workaround. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html