From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH 1/1] ipr: Fix for adapter shutdown issue Date: Wed, 15 Jun 2005 10:47:38 -0500 Message-ID: <1118850458.5045.34.camel@mulgrave> References: <200506151515.j5FFFNQA020480@d01av01.pok.ibm.com> <1118849292.5045.27.camel@mulgrave> <42B04A9C.7050503@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from stat16.steeleye.com ([209.192.50.48]:20904 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S261190AbVFOPrk (ORCPT ); Wed, 15 Jun 2005 11:47:40 -0400 In-Reply-To: <42B04A9C.7050503@us.ibm.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: brking@us.ibm.com Cc: SCSI Mailing List , haren@us.ibm.com On Wed, 2005-06-15 at 10:34 -0500, Brian King wrote: > For scsi disks attached to an ipr adapter, the SYNCHRONIZE_CACHE command > gets sent to the disk and works just like when attached to any other > HBA. The ipr disk array devices, however, do not support the SYNC_CACHE command, > nor do they support the caching mode page, so SYNC_CACHE never gets sent. > So, the shutdown hook is needed to flush the adapter's battery backed write > cache for all attached disk arrays on system shutdown. Well, that means you have a whole lot more trouble in 2.6.12 than simply failing to flush a cache on shutdown. The barrier code now uses cache synchronization commands, so if you crash the on-disk image will not be what a journalling filesystem expects. As long as the battery keeps the information alive in the cache, I assume this corrects itself when ipr next powers up, but if you trusted this, you wouldn't be fussing about the shutdown cache flush, now would you? James