From owner-freebsd-current@FreeBSD.ORG Sun Mar 9 05:41:02 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 58FCA106566C for ; Sun, 9 Mar 2008 05:41:02 +0000 (UTC) (envelope-from duncan.young@pobox.com) Received: from out4.smtp.messagingengine.com (out4.smtp.messagingengine.com [66.111.4.28]) by mx1.freebsd.org (Postfix) with ESMTP id 2D5E38FC28 for ; Sun, 9 Mar 2008 05:41:02 +0000 (UTC) (envelope-from duncan.young@pobox.com) Received: from compute2.internal (compute2.internal [10.202.2.42]) by out1.messagingengine.com (Postfix) with ESMTP id 94846BD3D0 for ; Sun, 9 Mar 2008 00:25:31 -0500 (EST) Received: from heartbeat2.messagingengine.com ([10.202.2.161]) by compute2.internal (MEProxy); Sun, 09 Mar 2008 00:25:31 -0500 X-Sasl-enc: dfknf4D4BCJEIV2nWJ5x3smEekdlNQ7AZPgyPQ+vpPai 1205040331 Received: from triple0.qld.optushome.com.au (c210-49-75-149.rochd2.qld.optusnet.com.au [210.49.75.149]) by mail.messagingengine.com (Postfix) with ESMTPSA id 2479B24CD5 for ; Sun, 9 Mar 2008 00:25:31 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by triple0.qld.optushome.com.au (Postfix) with ESMTP id D6D99BC92 for ; Sun, 9 Mar 2008 15:25:27 +1000 (EST) From: Duncan Young To: freebsd-current@freebsd.org Date: Sun, 9 Mar 2008 15:25:26 +1000 User-Agent: KMail/1.9.7 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200803091525.27311.duncan.young@pobox.com> Subject: write cache on usb disks and zfs X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: duncan.young@pobox.com List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Mar 2008 05:41:02 -0000 Hi all I am having a few problems with external usb2 disk and write caching. I have some caddies which allow write caching (seen and editable via camcontrol) and others which automatically disable it. i.e. #camcontrol modepage da2 -m 8 IC: 0 ABPF: 0 CAP: 0 DISC: 0 SIZE: 0 WCE: 0 MF: 0 RCD: 0 Demand Retention Priority: 0 Write Retention Priority: 0 Disable Pre-fetch Transfer Length: 0 Minimum Pre-fetch: 0 Maximum Pre-fetch: 0 Maximum Pre-fetch Ceiling: 0 and #camcontrol modepage da2 -m 8 -e camcontrol: no editable entries I am trying to use the USB drives for backup and would like to use zfs on them, but the problem I have is with the cache disabled, I get lots of kernel: (da2:umass-sim0:0:0:0): SYNCHRONIZE CACHE. CDB: 35 0 0 0 0 0 0 0 0 0 kernel: (da2:umass-sim0:0:0:0): CAM Status: SCSI Status Error kernel: (da2:umass-sim0:0:0:0): SCSI Status: Check Condition kernel: (da2:umass-sim0:0:0:0): ILLEGAL REQUEST asc:20,0 kernel: (da2:umass-sim0:0:0:0): Invalid command operation code kernel: (da2:umass-sim0:0:0:0): Unretryable error errors in /var/log/messages. I am assuming that the error messages are harmless, but it would be nice for zfs to pay attention and not continually issue the commands. Is there a way to do this? Duncan