<[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... > We are using VSAM Linear datasets (LDS) and Data-in-Virtual (DIV) > within our application and this is working fine - apart from under one > circumstance. > > If we define a VSAM LDS as multi-volulme and capable of over 4GB by > setting the Extended-Addressability option we can see some very severe > throughput problems when the actual LDS starts using the 2nd and > subsequent Data Volumes. > > STROBE shows that there is a big long I/O chain that seems to indicate > that the underlying I/O is doing sequential reads from the start of > each new volume - this in turn causes severe delays to the > application. > > We have seen our application wiz through the first DASD volume and > then go into a cycle of "wait nearly 2 minutes, wake up and do a small > bit of activity and then go to sleep again". Over a period of 4+ hours > our application used 1.5 minutes of CPU time. > > The final dataset was written ok, it took just far far too long to > deliver. > > We are sure that it is NOT our application code and that it must be > something to do with DIV and its underlying I/O. > > Has any ever seen anything like this and has some advice/feedback to > share? > Thanks, Steve >
Steve, This sounds a little like a problem we discovered with Bookmanager. It appears to be an FSEEK() LE problem with multivolume datasets. On a single volume dataset, performance is good, on a multivolume dataset performance is terrible. The APAR number is PK50785. We received some fixes, but they did not fully solve the problem, just improved performance somewhat. Maybe this helps. 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: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
