We only have four "DASD" FICON channels from each z10 (2). So all LCUs share the same eight channels (four from each processor). Each FICON channel can handle multiple concurrent I/O's (FICON handles eight concurrent operations?). I don't know how many concurrent I/Os a DS8000 LCU can handle. Would it be 64 (2 processors x 4 channels/processor x 8 operations/channel) or some lesser number? If it 32/processor, then what I am worrying about?
-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Ron Hawkins Sent: Thursday, January 21, 2010 12:05 PM To: [email protected] Subject: Re: PAGE datasets -- few large or more small Don, At a guess you probably have eight channels per LCU, and your volumes are configured on RAID-5 with 6+P+S or 7+P. In terms of potential parallel IO that makes eight locals look really good as a starting point for handling your peaks. If you have more paths and array groups then you can always have more than eight locals. You can use Custom Sized Volumes to allocate many, small volumes for Locals, or with Dynamic PAV you can put many small locals on one volume - one volume still has eight channels and 7 or eight underlying HDD. Note that the number of HDD is important for Page-ins, as they are usually cache misses. EMC and HDS customers can use Permacache or FlashAccess to create cache-locked Page Datasets for better-than-Flashdrive paging performance. Ron ---------------------------------------------------------------------- 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
