*Yes*. Hardware improvements have reduced the impact, but the issue still exists. Think lots of itty-bitty datasets on a mod 9.
You previously had 3 "logical" actuators to access 3 units of data . With mod 9 you have 1 "logical" actuator to access the same amount of data. From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Jousma, David Sent: Monday, January 23, 2012 9:18 AM To: IBM-MAIN@bama.ua.edu Subject: Re: Going from mod-3 to mod9 Iosq? Really? This is raid dasd, isn't "slow" 3390-9's a thing of the past? From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Staller, Allan Sent: Monday, January 23, 2012 10:09 AM To: IBM-MAIN@bama.ua.edu Subject: Re: Going from mod-3 to mod9 <snip> 1. We just had 3390-9's configured into our EMC box. This box also contains 3390-3's. Given that the hardware is the same throughout and all other things being equal, is there any decrease in response time on the mod-9's? </snip> Beware of IOSQ! From the viewpoint of the Operating System, you now have 3 times as much data behind the actuator on Mod-9's as Mod-3's. If the Operating system *thinks* the device is busy, the IO is queued off the UCB and never even tried until it comes to head of queue. Multi-system access will exacerbate this even more. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
