-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of David Crayford Sent: Wednesday, June 05, 2013 15:19 To: [email protected] Subject: Re: I/O Optimization
>> BTW, is the reason FBS is fast for seeks because it makes it easier >> to calculate the track position for a POINT? I've never seen FBS used before. > I don't know what IBM uses under the covers, but it's probably the > same thing that SAS/C did. Calculate the CCHHR from the byte offset > and use EXCP to read the block directly. No need to use POINT. FBS is > guaranteed not to have any short blocks, so the calculation is trivial. > Where does "spanned" come into play? Why does that make the difference? Multiple uses of the letter S: VBS = Variable Block Spanned FBS = Fixed Block Special Kees. ******************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 ******************************************************** ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
