From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars Marowsky-Bree Subject: Re: Re: fastfail operation and retries Date: Fri, 22 Apr 2005 00:24:09 +0200 Message-ID: <20050421222409.GY17315@marowsky-bree.de> References: Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development Cc: Linux SCSI , aherrman@de.ibm.com List-Id: linux-scsi@vger.kernel.org On 2005-04-21T23:33:57, Andreas Herrmann wrote: > Well, there are various situations when all paths to the ESS are > "temporarily unavailable". In some cases TASK_SET_FULL/BUSY is > reported as it should be. Not sure whether this sense data is decoded and handled correctly in dm-mpath yet. I don't have detailed specs, nor a feature request to allocate time to work on making sure it really does. I recommend that someone at IBM takes the real specs for the ESS and makes sure that it all works, by a combination of the right defaults in the multipath-tools hwtable and, if need be, a dm-ess plugin to handle this. This would be much appreciated. > underruns or exchange sequences are aborted and finally it might be > that requests just time out. BTW, it is not only ESS where I have seen > such (broken) behaviour. Well, what can I say. Broken behaviour needs to be documented and worked around, but obviously only as far as that is possible. > > It is possible that to fully support them a dm mpath hardware handler > > (like for the EMC CX family) might be required, too. > For the time being I hope "queue_if_no_path" feature is sufficient > to succesfully pass our tests ;-) If it is sufficient, you might at least wish to update the multipath-tools hwtable entry so that it is automagically set for your arrays. Sincerely, Lars Marowsky-Br=E9e --=20 High Availability & Clustering SUSE Labs, Research and Development SUSE LINUX Products GmbH - A Novell Business