[EMAIL PROTECTED] (Ed Gould) writes: > I have been exposed to two different "channel extenders" over the > years. Of the two each had its own weaknesses. I won't talk about > brand names other than to say they were from different parts of the US. > The first (and second) seemed to drive IOS nuts and they were guilty > of various errors which at least a few times brought the system down > (these were attached to either a 4341 or a 168 (& 3033)). I had IBM > ask me to strip out their logrec errors of the report as the number > of errors at times amounted to several hundred a day. > > Yes the damn things worked (sort of kind of) but the error recovery > took its toll on MVS. The devices they had at the other end had > response time issues which were hard to pin down as to where the > issue was. The error recovery was part of issue of course but other > items just kept on cropping up and (at times) it was a part time > sysprog to baby sit the various issues.
recent posting about doing channel extender installation in 1980, when STL (now silicon valley lab) was bursting at the seams and needed to move 300 (IMS) to offsite bldg. http://www.garlic.com/~lynn/2006y.html#3 The Future of of CPUs: What's After Multi-core one of the things i did was choose to reflect "channel check" when i got unrecoverable error (some number from the T1 link). that decision eventually propogated into a number of different implementations supporting the same hardware. this showed up as a problem early in the 3090 product cycle. after first year, 3090 product manager contacted me claiming that the 3090 customer machines erep was showing an "unnatural" number of channel checks. 3090 was designed to have something like 3-5 total, aggregate, channel checks for the first year across all installed 3090s. erep reports had turned up something like 20 total channel checks. after some investigation, i determined that IFCC (interface control checks) would result in the same error recovery process (as reflecting channel check). installation supported channel attached 3270 controllers, printers, and tapes. didn't support CKD DASD ... because of timing dependent problems with search arguments. later the vendor introduced enhanced "remote device adapter" that addressed the timing problem with CKD search arguments. You saw this show up at installations like NCAR ... besides supporting ibm mainframe channel extension it also supported a number of other vendor processors. the NCAR installation sort of used an ibm mainframe system as a hierarchical filesystem control infrastructure ... for other processors (like Crays) directly doing i/o to CKD disks (sort of the original SAN implementation). this particular vendor eventually was later purchased by STK. misc. past posts on this subject: http://www.garlic.com/~lynn/94.html#23 CP spooling & programming technology http://www.garlic.com/~lynn/94.html#24 CP spooling & programming technology http://www.garlic.com/~lynn/96.html#27 Mainframes & Unix http://www.garlic.com/~lynn/2000b.html#38 How to learn assembler language for OS/390 ? http://www.garlic.com/~lynn/2000c.html#65 Does the word "mainframe" still have a meaning? http://www.garlic.com/~lynn/2000c.html#68 Does the word "mainframe" still have a meaning? http://www.garlic.com/~lynn/2001.html#21 Disk caching and file systems. Disk history...people forget http://www.garlic.com/~lynn/2001.html#22 Disk caching and file systems. Disk history...people forget http://www.garlic.com/~lynn/2001g.html#33 Did AT&T offer Unix to Digital Equipment in the 70s? http://www.garlic.com/~lynn/2001k.html#46 3270 protocol http://www.garlic.com/~lynn/2002.html#10 index searching http://www.garlic.com/~lynn/2002e.html#46 What goes into a 3090? http://www.garlic.com/~lynn/2002f.html#7 Blade architectures http://www.garlic.com/~lynn/2002f.html#60 Mainframes and "mini-computers" http://www.garlic.com/~lynn/2002g.html#61 GE 625/635 Reference + Smart Hardware http://www.garlic.com/~lynn/2002i.html#43 CDC6600 - just how powerful a machine was it? http://www.garlic.com/~lynn/2002j.html#67 Total Computing Power http://www.garlic.com/~lynn/2003b.html#29 360/370 disk drives http://www.garlic.com/~lynn/2003c.html#66 FBA suggestion was Re: "average" DASD Blocksize http://www.garlic.com/~lynn/2003g.html#22 303x, idals, dat, disk head settle, and other rambling folklore http://www.garlic.com/~lynn/2004d.html#75 DASD Architecture of the future http://www.garlic.com/~lynn/2004e.html#33 The attack of the killer mainframes http://www.garlic.com/~lynn/2004p.html#29 FW: Is FICON good enough, or is it the only choice we get? http://www.garlic.com/~lynn/2005e.html#13 Device and channel http://www.garlic.com/~lynn/2005n.html#1 Cluster computing drawbacks http://www.garlic.com/~lynn/2005r.html#14 Intel strikes back with a parallel x86 design http://www.garlic.com/~lynn/2005r.html#55 IBM 3330 http://www.garlic.com/~lynn/2005u.html#22 Channel Distances http://www.garlic.com/~lynn/2005u.html#23 Channel Distances http://www.garlic.com/~lynn/2006i.html#34 TOD clock discussion http://www.garlic.com/~lynn/2006u.html#19 Why so little parallelism? ---------------------------------------------------------------------- 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
