Bill, This is not quite right. FICON is restricted by the either the number of OE supported by the channel, or the OE supported by the Storage port. On a z9 there can be 64 OE on every channel on an LCU - with eight channels that's 512 IO that can be transferring data or disconnected and waiting for a cache miss, TrueCopy RIO or such like at the same time.
AFAIK there is no MVS restriction on the number of alias assigned to a device. You can have one base address with all 255 alias assigned if that is something useful. Datasets that are good candidate for FlashAccess would probably benefit for this sort of unique setup. High activity volumes with a good cache hit rate on Wide Stripe PG would also benefit. There were some restriction on the number of alias in EMC and HDS a few generations ago, but not in current models. Note that ESCON also did not have a restriction of one IO per channel. There could only be one data transfer per ESCON channel, but when an IO disconnected another IO could jump straight in and use the channel. There could be any number of IO in a Disconnect state, but only one IO per channel connected. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of (IBM Mainframe Discussion List) > Sent: Friday, September 07, 2007 6:40 AM > To: [email protected] > Subject: Re: [IBM-MAIN] Dynamic PAV Device Limit? > > > > In a message dated 9/7/2007 7:59:47 A.M. Central Daylight Time, > [EMAIL PROTECTED] writes: > >I have not been able to find any statement about whether WLM will put > any limit on the number of aliases that can be assigned to a > particular device when using Dynamic PAVs. Does anyone on the list > know of a limit? Can anyone point me to a manual that would document > whether this can occur or not? > > I don't know what WLM uses as a limit, if any, but the I/O hardware has > a > limit of eight simultaneously active I/O > requests to any one given device. Even if you have 100 aliases, there > can > still only be eight I/Os involving that one > device occurring at the same time. These eight can come from eight > different LPARs or all from one LPAR. This hardware > limit of eight is true whether the PAVs are dynamic or static. I > can't > quickly find a document with the number eight in it, > but it's in patent applications that I have studied. > > Bill Fairchild > Plainfield, IL > > > > > > ************************************** Get a sneak peek of the all-new > AOL at > http://discover.aol.com/memed/aolcom30tour > > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- 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
