Re: RES: Implicit VVDS creation
In bc6b7b77ef4d5e4bb95b0559a0d6d5e10531ce9...@mx3.state.nv.us, on 02/06/2014 at 01:17 PM, David G. Schlecht dschle...@admin.nv.gov said: Or am I way off base? At least partially. On a simulated 3390 a cylinder boundary may not tell you much about seek time, but it can still have an effect on whether a channel program breaks and has to be restarted. OTOH, with code that builds an ECKD channel program that has a lot less impact on performance than it used to. -- Shmuel (Seymour J.) Metz, SysProg and JOAT ISO position; see http://patriot.net/~shmuel/resume/brief.html We don't care. We don't have to care, we're Congress. (S877: The Shut up and Eat Your spam act of 2003) -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: RES: Implicit VVDS creation
On 02/06/2014 05:42 PM, Shmuel Metz (Seymour J.) wrote: In bc6b7b77ef4d5e4bb95b0559a0d6d5e10531ce9...@mx3.state.nv.us, on 02/06/2014 at 01:17 PM, David G. Schlecht dschle...@admin.nv.gov said: Or am I way off base? At least partially. On a simulated 3390 a cylinder boundary may not tell you much about seek time, but it can still have an effect on whether a channel program breaks and has to be restarted. OTOH, with code that builds an ECKD channel program that has a lot less impact on performance than it used to. ...and if the physical storage media still has an access-time function which tends to be larger when separation on the physical media is larger, it is not unreasonable to expect that any emulated 3390 strategy which utilizes a fixed mapping would likely use some sequential allocation strategy which would at least show a statistical bias for faster access to blocks that were closer together on the emulated device, as that would improve the odds (but not guarantee) they are closer together on the physical media as well. Such access-time bias would no doubt vary in a manner that couldn't be usefully predicted from emulated DASD architecture, but it seems reasonable that it should exist. In a practical sense though, one could argue that any data that is being accessed frequently enough to be a performance concern would be interacting with DASD cache storage in ways that could completely mask the difference in physical access times; so the controlled placement of VTOC, VTOCIX, and VVDS these days is more a matter of aesthetics and emulated-media fragmentation avoidance than performance. -- Joel C. Ewing,Bentonville, AR jcew...@acm.org -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
RES: Implicit VVDS creation
Since z/OS 1.13 there is a new IGGCATxx member in PARMLIB that can be used to specify VVDS default space, among other parameters. Atenciosamente / Regards / Saludos Ituriel do Nascimento Neto BANCO BRADESCO S.A. 4250 / DPCD Engenharia de Software Sistemas Operacionais Mainframes Tel: +55 11 3684-2177 R: 42177 3-1402 Fax: +55 11 3684-4427 Agora é BRA. BRA de Brasil. BRA de Bradesco. Patrocinador oficial dos Jogos Olímpicos e Paralímpicos Rio 2016. -Mensagem original- De: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] Em nome de David G. Schlecht Enviada em: quinta-feira, 6 de fevereiro de 2014 15:55 Para: IBM-MAIN@LISTSERV.UA.EDU Assunto: Re: Implicit VVDS creation Hold the presses! The documents for v1r13 say the VVDSSIZE defaults to TRKS(10 10). Holy cow, that's a whole lot less than 10 cylinders. One would think that at 10 tracks, the VVDS would run out of space (and extents) quite frequently but I don't see this being a frequent topic on IBM-MAIN. David G. Schlecht | Information Technology Professional State of Nevada | Department of Administration | Enterprise IT Services T:(775)684-4328 | F: (775) 684‐4324 | E:dschle...@admin.nv.gov -Original Message- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of David G. Schlecht Sent: Thursday, February 06, 2014 9:22 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Implicit VVDS creation Does anyone still build VVDS datasets explicitly when initializing volumes? I understand that the default allocation for a new VVDS is CYLS(10 10) which saves me from having to rebuild the VVDS if it fills up. What is everyone else doing with VVDS datasets? Is there still a valid argument for building them explicitly? David G. Schlecht | Information Technology Professional State of Nevada | Department of Administration | Enterprise IT Services T:(775)684-4328 | F: (775) 684‐4324 | E:dschle...@admin.nv.gov This communication, including any attachments, may contain confidential information and is intended only for the individual or entity to which it is addressed. Any review, dissemination or copying of this communication by anyone other than the intended recipient is strictly prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and delete all copies of the original message. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN AVISO LEGAL br...Esta mensagem é destinada exclusivamente para a(s) pessoa(s) a quem é dirigida, podendo conter informação confidencial e/ou legalmente privilegiada. Se você não for destinatário desta mensagem, desde já fica notificado de abster-se a divulgar, copiar, distribuir, examinar ou, de qualquer forma, utilizar a informação contida nesta mensagem, por ser ilegal. Caso você tenha recebido esta mensagem por engano, pedimos que nos retorne este E-Mail, promovendo, desde logo, a eliminação do seu conteúdo em sua base de dados, registros ou sistema de controle. Fica desprovida de eficácia e validade a mensagem que contiver vínculos obrigacionais, expedida por quem não detenha poderes de representação. LEGAL ADVICEbr...This message is exclusively destined for the people to whom it is directed, and it can bear private and/or legally exceptional information. If you are not addressee of this message, since now you are advised to not release, copy, distribute, check or, otherwise, use the information contained in this message, because it is illegal. If you received this message by mistake, we ask you to return this email, making possible, as soon as possible, the elimination of its contents of your database, registrations or controls system. The message that bears any mandatory links, issued by someone who has no representation powers, shall be null or void. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: RES: Implicit VVDS creation
One of the reasons to do it implicitly is placement, not that it really matters, but if you want it next to the VTOC you may want to do it implicitly. On Thu, 6 Feb 2014 18:01:51 +, ITURIEL DO NASCIMENTO NETO 4254.itur...@bradesco.com.br wrote: Since z/OS 1.13 there is a new IGGCATxx member in PARMLIB that can be used to specify VVDS default space, among other parameters. Even though the storage team implicitly defines a VVDS at the shop I spend time it (usually?), we had this command in place prior to z/OS 1.13: F CATALOG,VVDSSPACE(30,15) So 3x larger for primary than the default TRK(10,10). Now we have it in IGGCATxx since z/OS 1.13 as mentioned. VVDSSPACE(30,15) /* DFLT IS 10,10 */ Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS ITIL v3 Foundation Certified mailto:m...@mzelden.com Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html Systems Programming expert at http://search390.techtarget.com/ateExperts/ -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: RES: Implicit VVDS creation
I was curious about this aspect, as well. Since 3390 emulation is just emulation, and usually the number of cylinders in the physical device do not match the number being emulated, the layout on the cylinder on the emulated 3390 (defined in JCL) is nothing like how it is actually stored on the physical device. So expecting something to be on a cylinder boundary seems likely wrong. This shortcoming seems to apply equally to a DS8000 as any other device such as an EMC. What's more, on some physical devices, there's no such thing as a cylinder. Or am I way off base? David G. Schlecht | Information Technology Professional State of Nevada | Department of Administration | Enterprise IT Services T:(775)684-4328 | F: (775) 684‐4324 | E:dschle...@admin.nv.gov -Original Message- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Mark Zelden Sent: Thursday, February 06, 2014 10:45 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: RES: Implicit VVDS creation One of the reasons to do it implicitly is placement, not that it really matters, but if you want it next to the VTOC you may want to do it implicitly. On Thu, 6 Feb 2014 18:01:51 +, ITURIEL DO NASCIMENTO NETO 4254.itur...@bradesco.com.br wrote: Since z/OS 1.13 there is a new IGGCATxx member in PARMLIB that can be used to specify VVDS default space, among other parameters. Even though the storage team implicitly defines a VVDS at the shop I spend time it (usually?), we had this command in place prior to z/OS 1.13: F CATALOG,VVDSSPACE(30,15) So 3x larger for primary than the default TRK(10,10). Now we have it in IGGCATxx since z/OS 1.13 as mentioned. VVDSSPACE(30,15) /* DFLT IS 10,10 */ Mark -- Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS ITIL v3 Foundation Certified mailto:m...@mzelden.com Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html Systems Programming expert at http://search390.techtarget.com/ateExperts/ -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
