I notice the following scenario. Not sure if this is relevant to your question.
- I use a graphical client for Windows to z/OS FTP (Ipswitch WS_FTP Pro, FWIW) - If it has more than one member (to one PDS/E) to transfer it will start about three or so transfers in parallel - I *sometimes* -- have not bothered to nail it down -- have one or two of the transfers fail on "access prohibited" or some such. I retry and it succeeds. There is no one else accessing the PDS/E, so I think it is some sort of ENQ "misunderstanding." My mental image is that one transfer obtains an ENQ on the entire PDS, and then another fails at obtaining that ENQ, but I don't know. - FWIW, I also transfer multiple files the same way to a USS path, a lot more often than to a PDS/E. It never fails in this way. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Kirk Wolf Sent: Tuesday, December 06, 2016 1:16 PM To: [email protected] Subject: FTP serialization when writing PDS/PDSE members As many are aware, z/OS Comm Svr FTP uses DISP=SHR + ISPF compatible ENQs when writing PDS members. See for example this message for evidence: ======================= EZA2563W Data set dsname used exclusively by someone else. Explanation: A data transfer (get, put or append) of a partitioned data set (PDS) was requested and the member requested is currently in use. ==================== I am curious about how this actually works, specifically how/when FTP holds the exclusive *data set* ENQ (QNAME=SPFEDIT,RNAME=DSN). This would be the (hopefully short) ENQ that is held while actually doing I/O to the data set. What would happen if the FTP transfer started, this data set ENQ was obtained, and then the transfer hung for some period of time? Wouldn't that be bad? Or, perhaps FTP buffers the data for a PDS member write in memory until it has the complete member before doing I/O? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
