From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boaz Harrosh Subject: Re: [usb-storage] USB storage devices and SAT Date: Tue, 05 Aug 2008 19:09:48 +0300 Message-ID: <48987B4C.7020901@panasas.com> References: <489872F7.8050703@torque.net> <48987856.9030804@panasas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from gw-colo-pa.panasas.com ([66.238.117.130]:1025 "EHLO natasha.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752901AbYHEQKM (ORCPT ); Tue, 5 Aug 2008 12:10:12 -0400 In-Reply-To: <48987856.9030804@panasas.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: dougg@torque.net Cc: Alan Stern , USB Storage list , "linux-scsi@vger.kernel.org" , Matthieu castet Boaz Harrosh wrote: > Douglas Gilbert wrote: >> The "correct" maximum value (SPC-3 and draft SPC-4) is 252. >> Since SPC-3 the recommended maximum length for the basic >> SCSI commands that have a 1 byte allocation length field was >> altered from 255 to 252. This is to be a little friendlier >> to transports that move data in 4 byte units across their >> transport. Guessing a bit here but SATA, SAS and FCP fall >> into that group of transports. > > 252 + 8 bytes header for REQUEST_SENSE command. So total > 260 buffer size. (Last I look) > OK you are right 252 allocation length max, specified at REQUEST_SENSE CDB. The sense_buffer structure itself has 252 + 8 restriction which got me confused. In OSD we have large sense payload that can get truncated by these values. Boaz