From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurence Oberman Subject: Re: What partition should the MTMKPART argument specify? Was: Re: st driver doesn't seem to grok LTO partitioning Date: Thu, 21 Jan 2016 17:06:03 -0500 (EST) Message-ID: <1281192568.8282297.1453413963788.JavaMail.zimbra@redhat.com> References: <20151218170644.24167419@harpe.intellique.com> <688812570.3359420.1452030904683.JavaMail.zimbra@redhat.com> <20160106161049.34f29973@harpe.intellique.com> <1993563395.3556606.1452093814452.JavaMail.zimbra@redhat.com> <20160106170720.61db9e86@harpe.intellique.com> <1371374871.6203837.1452802373256.JavaMail.zimbra@redhat.com> <0840949A-970D-43FB-A691-E2F8AC2A0804@kolumbus.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mx3-phx2.redhat.com ([209.132.183.24]:45794 "EHLO mx3-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751237AbcAUWGQ convert rfc822-to-8bit (ORCPT ); Thu, 21 Jan 2016 17:06:16 -0500 In-Reply-To: <0840949A-970D-43FB-A691-E2F8AC2A0804@kolumbus.fi> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Kai =?utf-8?Q?M=C3=A4kisara_=28Kolumbus=29?= Cc: Shane M Seymour , Emmanuel Florac , Laurence Oberman , linux-scsi@vger.kernel.org Given what we see at customers I am leaning towards the SCSI level <=3D= 2 to ensure the older LTO5's are supported. The newer ones should be backwards compatible. I may have an older LTO5 showing up that wont need a F/W update to work= , and will be able to add a "tested by" once I get it. But lets see what the others have to say Laurence Oberman Principal Software Maintenance Engineer Red Hat Global Support Services ----- Original Message ----- =46rom: "Kai M=C3=A4kisara (Kolumbus)" To: "Shane M Seymour" Cc: "Laurence Oberman" , "Emmanuel Florac" , "Laurence Oberman" , linux-scsi= @vger.kernel.org Sent: Thursday, January 21, 2016 3:58:46 PM Subject: What partition should the MTMKPART argument specify? Was: Re: = st driver doesn't seem to grok LTO partitioning > On 15.1.2016, at 2.21, Seymour, Shane M wrote= : >=20 > Unfortunately I'm unable to lay my hands on an LTO 5 tape drive so I'= m not able to test that it works either. If it helps at all I can test = in the negative and make sure that for an LTO 3 drive it fails graceful= ly but that's about it at the moment. Thanks for all testers and those who attempted to test. The latest patc= h applies the standard quite strictly and I think it should work with m= ost drives. The implementation can be fixed later if problems are found= =2E However, before making the final patch, we should decide which partitio= n the specified size should apply to. For the SCSI level <=3D2 it appli= es to partition 1. For other drives we may have some freedom to =E2=80=9C= tune=E2=80=9D the definition. The size should apply to the partition th= e users expect it to apply.=20 The current documentation says "the argument gives in megabytes the siz= e of partition 1 that is physically the first partition of the tape=E2=80= =9D. The documentation I have found for current drives (HP and IBM LTO,= IBM 3592, Storagetek T1000) all number the partitions sequentially fro= m the start of the tape. The access time for any partition is probably = about the same when wrapwise partitioning is used. It does matter with = linear partitioning. Unfortunately, the standards leave the numbering t= o the implementor. Partitioning with two partitions is used for storing index in a small p= artition and use the rest of the tape for data. In this case, it is pro= bably natural to specify the size of the index. The LTFS definition sup= ports index in any partition. The open source code I have seen seem to = default to index in partition 0. The HP and IBM LTO default partitioning (FDP=3D1) specifies two wraps (= minimum) to partition 1 and the rest to 0. There seem to be lot of arguments supporting both possible choices. Sho= uld we use the existing definition (1) or change it for the drives supp= orting SCSI level >=3D 3 (or supporting FORMAT MEDIUM)? The definition = can=E2=80=99t be changed later. This is why we should make a good decis= ion. Opinions? Thanks, Kai -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html