I agree If by definition you can only have one I/O operation active to a UCB, then by supplying PAV's to virtualize, or multipath the UCB you can get multiple I/O's to the same UCB.
I have been very reluctant to push use of 3390-9 DASD volumes for SFS and/or users with large file requirements. For a single user/file this should not be an issue. Say you have a single repository or file system that is shared with other guests, than the I/O subsystem becomes a bottle neck. and when you get to DASD volumes with over 30,000 Cylinders, this will be even more a problem. I would be interested in other peoples Ideas concerning these assumptions. Larry Davis, \|/ Nielsen Media Research (. .) VM Systems Programmer ___ooO-(_)-Ooo___ mailto:[EMAIL PROTECTED] -----Original Message----- From: Post, Mark K [mailto:[EMAIL PROTECTED]] Sent: Tuesday, March 12, 2002 16:06 To: [EMAIL PROTECTED] Subject: Re: PAV Support - any requirement for it ? Ingo, Yes, I would say there is a requirement for it, either running in an LPAR, or under VM. _VM_ has a requirement for PAV. Anyone who wants to build a large volume and access it from multiple processes with any reasonable performance has a requirement for PAV. File servers, database servers, etc., etc. Barton Robinson recommends emulating the smallest DASD devices possible to get decent performance out of them, due to the lack of PAV support in VM. That's going to be a real problem for people who have large files they need to be able to support. Mark Post -----Original Message----- From: Ingo Adlung [mailto:[EMAIL PROTECTED]] Sent: Tuesday, March 12, 2002 11:42 AM To: [EMAIL PROTECTED] Subject: PAV Support - any requirement for it ? I'd like to gather your feedback on the requirement for Linux exploiting Parallel Access Volume (PAV) support available on ESS (Shark) storage subsystems and its competitors in the market. In the past some customers expressed their concern about the data throughput ESCON attachments provide, which made us think about PAV support. However, I would appreciate any thoughts about FICON based storage attachments already satisfying your throughput requirements or whether you consider PAV exploitation a major requirement nonetheless ? Any opinions ? e.g. do you see requirements for it as you can't move to FICON in the forseeable future ? I would appreciate your feedback, either offline or to this list. In any case I would appreciate if you could also depict the business scenario / solution you expect PAV exploitation being a requirement for. Thanks and best regards, Ingo ********************************************************************** Ingo Adlung, Linux for zSeries - Strategy & Design The box said, 'Requires Windows95 or better', ...so I installed LINUX.
